Symposium Organizers
Alexander Cartwright State University of New York-Buffalo
Thomas M. Cooper Air Force Research Laboratory
Anna Koehler University of Potsdam
Kirk S. Schanze University of Florida
BB1: Hybrid Chromophores for Linear and Nonlinear Optics Applications I
Session Chairs
Tuesday PM, April 10, 2007
Room 2020 (Moscone West)
10:00 AM - BB1.2
Effect of meso-substitution and β-bromo Substitution on the Photophysical Properties of Porphyrins.
Joy Rogers 1 2 , Weijie Su 1 3 , Jonathan Slagle 1 3 , Jennifer Monahan 1 , Daniel McLean 1 4 , Augustine Urbas 1
1 Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, Ohio, United States, 2 , UES, Inc., Dayton, Ohio, United States, 3 , AT&T Government Solutions, Dayton, Ohio, United States, 4 , Science Applications International Corporation, Dayton, Ohio, United States
Show AbstractInterest in both the linear and non-linear properties of porphyrins has been large for quite some time because of their use in numerous applications such as cancer therapy, alternative energy, hemoprotein models, and electronics.1 Porphyrins are especially interesting because small changes in their structure lead to large changes in their electronic and photophysical properties. Therefore making them excellent candidates for studying structure-property relationships. We have recently synthesized and studied a series of meso-carbazole and meso-triphenylamine octabromoporphyrins. Various changes have been made to the porphyrins such as the central metal, changes at the meso position, and addition of bromine to the β-position. We are interested in the effect of the addition of triphenylamine and carbazole in the meso position as well as the addition of the bromines to the triplet excited state properties. In general we observe a large triplet excited state absorption in the near infrared region and a dramatic shortening of the triplet excited state lifetime upon the addition of the bromine. This is expected due to the heavy atom effect of the bromine but is also consistent with more distortion of the porphyrin structure. The overall findings will be discussed in more detail. 1)Milgrom, L.R. The Colours of Life Oxford University Press New York: 1997.
10:15 AM - BB1.3
Examination of 2,2'-bipyridine Core Chromophores with Associated Metal/organic Complexes for Nonlinear Optical Absorption Activity.
John Peak 1 , Kye-Young Kim 1 , Kirk Schanze 1
1 Chemistry, Univ. of Florida, Gainesville, Florida, United States
Show Abstract10:30 AM - **BB1.4
Light-matter Interaction of Strong Laser Pulses in the Micro-, Nano-, and Pico-second Regimes.
Hans Agren 1
1 Biotechnology, Theoretcial Chemistry, Stockholm Sweden
Show Abstract11:30 AM - BB1.5
Novel Chromophore Containing Segmented Polyurethanes with Light Switchable Index of Refraction
Claus Eisenbach 1 , Min Mack 1
1 Institute for Polymer Chemistry, Universitaet Stuttgart, Stuttgart Germany
Show AbstractSegmented polyurethanes with anthracene building blocks for the hard segment have been synthesized. Model studies of the photocyclodimerization of the anthracene moieties incorporated into the hard segment have shown that such nanophase separated systems fulfill the requirement of a correct positioning of the reaction partners: The incompatibility of the hard and soft segments together with a nucleation effect of the built-in anthracene result in nanosize hard domains with the required spatial arrangement of the anthracene moieties. Repeated photodimerization-photocleavage cycles that result in a change of the bulk refractive index of the polyurethane film are possible. The hard segment structure as given, e.g., by the type of diisocyanate was identified to be an important parameter controlling the photochromism. The proof of principle and the implications for coatings technology will be discussed.
12:15 PM - BB1.8
Effects of Fluorination and Hydrogen Bonding Motif in a Series of Electro-Optically-Active Chromophores and their Physically Vapor Deposited Films.
David Frattarelli 1 , Michele Schiavo 1 , Antonio Facchetti 1 , Tobin Marks 1 , Mark Ratner 1
1 Chemistry, Northwestern University, Chicago, Illinois, United States
Show AbstractThe organization of nonlinear optical chromophores into a noncentrosymmetric architecture has been a lingering challenge in organic electro-optics (EO). The most recent approach to fabricating acentric/ EO-active films, physical vapor deposition (PVD), is employed for growth of a variety of thin films. Here, a series of new chromophores suitable for PVD are modeled and synthesized. These chromophores are characterized by the presence of H-bonding donor and acceptor groups as well as fluorinated molecular fragments to enhance volatility, thermal stability, and film forming properties. Molecular modeling reveals that for some chromophores both fluorination and H-bonding donor substitution increase β by 155 and 1381 × 10-30 esu respectively compared to the parent model system (PEPCOOH). Furthermore, conjugative decoupling between the chromophore π-donor and the H-bonding donor sites also increase β by 12 × 10-30 esu. In addition to the response trends, cluster calculations also reveal additivity in β for all benzoic acid containing chromophores up to three monomeric units in length. Experimental second harmonic generation (SHG) spectroscopy confirms trends in calculated responses, with χ2 increasing by 135 pm/V upon fluorination and 281 pm/V with H-bonding donor substitution. Also, compared to the cluster calculations, linear growth is observed by SHG for benzoic acid containing chromophore films up to one micron in thickness. Together, theoretical modeling and SHG play a critical role in helping better understand the structure-function relationship at both the molecular and macroscopic (film) levels, in addition to aiding the identification of new higher β chromophores with stronger χ2 responses, further advancing the field of electro-optical materials.
12:30 PM - BB1.9
A Marcus Theory Description of Triplet Energy Transfer.
Lekshmi Devi 1 2 , Carsten Dosche 2 , Mohamad Al-Suti 3 , Muhammed Khan 3 , Richard Friend 1 , Anna Koehler 2
1 Cavendish Laboratory, University of Cambridge, Cambridge United Kingdom, 2 Institute of Physics, University of Potsdam, Potsdam Germany, 3 Department of Chemistry, College of Science, Sultan Qaboos University, Al-Khod Oman
Show AbstractBB2: Hybrid Chromophores for Linear and Nonlinear Optics Applications II
Session Chairs
Tuesday PM, April 10, 2007
Room 2020 (Moscone West)
2:30 PM - **BB2.1
Water Soluble Poly(aryleneethynylene)s and Their Uses as Sensory Materials.
Uwe Bunz 0 , Ik-Bum Kim 0 , Ronnie Phillips 0 , Bradley Carson 0
0 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractWe will discuss in this contribution the synthesis of water soluble poly(aryleneethynylene)s (PAE) and their uses as sensory materials. These fluorescent conjugated polymers show very unusual sensory responses when exposed to metal ions or to proteins. When sugar-substituted PAEs are used, bacterial and lectins can be deteceted by Stern Volmer quenching.
3:00 PM - BB2.2
Luminescent Organoboron Polymers
Frieder Jaekle 1 , Anand Sundararaman 1 , Yang Qin 1 , Kshitij Parab 1
1 Department of Chemistry, Rutgers University, Newark, New Jersey, United States
Show AbstractTwo new classes of luminescent organoboron polymers and their photophysical properties are described, where boron is either in tri- or tetracoordinated state.In tricoordinate organoboron compounds, interaction of the empty p-orbital on boron with an organic π-system has been shown to lead to interesting photophysical and electron-conducting properties; these types of compounds have consequently found widespread use in the fields of optical and electronic materials and as chemosensors. The respective polymeric analogs are particularly intriguing due to the opportunity of applying solution processing techniques for device fabrication and, in the case of sensor materials, the possibility of signal amplification effects. Some of the advantages of using a polymer side chain modification approach are that high molecular weights are easily obtained and that copolymers containing different functionalities can be realized. Even block copolymer architectures are accessible through living polymerization techniques. We have developed a facile route for incorporation of electron-deficient boron centers into the side-chain of polymers with polystyrene backbone. The relative Lewis acidities and the photophysical properties can easily be fine-tuned by introducing various chromophoric aryl groups to the boron centers. Most intriguingly, despite the non-conjugated backbone, the boron centers in the side-chain act in a cooperative manner as reflected in a remarkable signal amplification in their emission spectra upon coordination to fluoride.In an effort at developing new polymeric materials for LED applications, a modular one-pot approach for the synthesis of a series of well-defined organoboron quinolate polymers and the tuning of their photoluminescence is applied. A series of organoboron quinolate polymers was obtained in high isolated yields (65-85%) by treatment of PS-BPhBr with substituted 8-hydroxyquinoline derivatives (variation of R group). All boron polymers were fully characterized by multi-nuclear NMR spectroscopy, gel permeation chromatography in line with multi-angle laser light scattering (GPC-MALLS), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Luminescence studies of the polymers revealed distinct emission bands ranging from the blue to red (462 to 615 nm), depending on the substitution patterns on the quinolate ligands.
3:15 PM - BB2.3
Platinum(II) Acetylides for Optical Power Limiting; Synthesis Towards Solid State Materials.
Robert Westlund 1 , Eirik Glimsdal 2 , Mikael Lindgren 2 , Marcus Carlsson 3 , Bertil Eliasson 3 , Cesar Lopes 4 , Eva Malmstrom 1
1 KTH Fiber and Polymer Technology, Royal Institution of Technology, Stockholm Sweden, 2 Department of Physics, Norwegian University of Science and Technology, Trondheim Norway, 3 Department of chemistry, Umeå University, Umeå Sweden, 4 Department of Functional Materials, Swedish Defence Research Agency, Linköping Sweden
Show Abstract3:30 PM - BB2.4
Photophysics and Nonlinear Transmission of a Cyclometalated Platinum(II) 4,6-diphenyl-2,2'-bipyridyl Pentynyl Complex.
Wenfang Sun 1 , Pin Shao 1
1 Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota, United States
Show Abstract3:45 PM - BB2.5
Nonlinear Band Gap in a 1D Polymer Structure
James Shirk 1 , R. Lepkowicz 1 3 , Guy Beadie 1 , A. Ranade 2 , A. Hiltner 2 , E. Baer 2
1 Optical Sciences Division, Naval Research Lab, Washington, District of Columbia, United States, 3 Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, Terre Haute, Indiana, United States, 2 Macromolecular Science and Engineering, Case Western Reserve University , Cleveland, Ohio, United States
Show AbstractOptical polymer structures comprising many thousands of alternating layers of different polymers with layer thicknesses from a few microns down to 10 nm or less are readily fabricated by nanolayer forced assembly. These materials are particularly attractive for optical applications because they can be both large and robust. Materials several feet wide by yards long are readily fabricated. These layered films can perform useful optical functions. With an appropriate layer thickness, the optical properties are those of a 1D photonic crystal with some disorder. In the present work a nonlinear 1D polymer photonic crystal is described. In this material layers of a nonlinear polymer alternate with layers of a linear polymer. The layers are designed to be nearly index matched so that initially the transmission is high. The nonlinear polymer material possesses a large nonlinear refractive index as well as a nonlinear absorption. With increasing intensity or fluence the transmission decreases because of the formation of a band gap as the index mismatch between the dyed and undyed layers increases and because of nonlinear absorption in the nonlinear layer.The 1D polymer material studied here comprised 512 alternating layers. The nonlinear layer was polycarbonate doped with a high concentration of the nonlinear dye lead(II) tetrakis(4-cumylphenoxy)-phthalocyanine (PbPc(CP)4). The linear layers were polyethylene-terephthalate. The layer thicknesses were on the order of 80 nm, corresponding to a quarter wave length in the visible. The magnitude and shape of the induced nonlinear band gap was measured using a femtosecond white-light continuum transient absorption experiment. To insure an equal distribution and ratio of thicknesses of dyed to undyed layers, the 512 layer sample was pressed to two different overall thicknesses and hence different band gaps. One section of the sample had a band gap centered near the peak of the excited-state absorption of the lead phthalocyanine (approx. 520 nm). In the thicker second section of the structured polymer, the band gap was centered beyond 700 nm. By comparing the transmission of the two films with increasing incident fluence we were able to observe the formation of the band gap.The magnitude of the induced band gap depends on 1) the number of layers, 2) the individual layer thickness and the degree of disorder, 3) the initial refractive index contrast between the two layers, and 4) the complex nonlinear refractive index of the active nonlinear layer. Each of these properties has been measured. A simple static model of the observed band gap qualitatively accounts for the observed properties of this nonlinear 1D polymer photonic crystal.
4:30 PM - BB2.6
Conjugated Polymer-aided Supramolecular Self-organization of Fullerene Whiskers.
Nurmawati Muhammad Hanafiah 1 , Ajikumar Parayil 2 , Renu Ravindranath 1 , Suresh Valiyaveettil 1 2
1 Chemistry, National University Singapore, Singapore Singapore, 2 , Singapore-MIT Alliance, National University of Singapore, Singapore Singapore
Show Abstract4:45 PM - BB2.7
A Shape-controlled Method to Functionalize Multiwalled Carbon Nanotubes with Ni3S2: Their Formation Mechanism and Optical Properties.
Dae Joon Kang 1 2 3 , Jimin Du 1 2 3
1 Physics , Sungkyunkwan University, Suwon Korea (the Republic of), 2 SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon Korea (the Republic of), 3 Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon Korea (the Republic of)
Show Abstract5:00 PM - BB2.8
Nanoscopic Photoluminescence Memory as a Fingerprint of Complexity in Self-assembled alkylene/siloxane hybrids.
Luis Carlos 1 , Veronica de Zea Bermudez 2 , Vitor Amaral 1 , Silvia Nunes 2 , Nuno Silva 1 , Rute Ferreira 1 , Joao Rocha 3 , Celso Santilli 4
1 Physics, University of Aveiro/CICECO, Aveiro Portugal, 2 Chemistry and CQ-VR, University of Trás-os-Montes e Alto Douro, Vila Real Portugal, 3 Chemistry, University of Aveiro/CICECO, Aveiro Portugal, 4 Instituto de Química, UNESP, Araraquara–SP Brazil
Show AbstractComplex structures, such as living organisms or highly structured materials, share in common the fact that their inherent complexity may be accounted for by the tangled organization of a vast number of simple units. The complex behaviour arises not necessarily due to the atomic structure of the system, but to the orderly assembly of all, or part, of its constituents. Self-assembly of synthetic soft-matter components (polymers, liquid crystals, surfactants, colloids and organic/inorganic hybrids) results in regular hierarchically-organized structures. Here, we report on a photoluminescent highly-organized bilayer alkylene/siloxane hybrid self-assembled by intermolecular hydrogen bonding between amide groups, van der Waals interactions between the alkylene chains and an entropic term related to the organic-inorganic phase separation [1]. These factors are decisive for the emergence of a thermally-actuated photoluminescence memory effect induced by a reversible order-disorder phase transition of the alkylene chains involving ~30 lamellae (~150 nm). The reversibility of this phase transition is attained through a heating/cooling cycle (20-120 C) from which a hysteretic behaviour of the emission energy emerges. The initial emission energy value is recovered after ~300 h, following a logarithmic time dependence, due to the slow kinetics of the restoration of the hydrogen-bonded amide-amide network. The photoluminescence is thus responsive to the annihilation/formation of the amide-amide array displaying nanoscopic sensitivity, contrarily to the customary case for which the local environment around the emitter probe determines the emission features. Moreover, the emission energy logarithmic time dependence reflects hierarchically constrained dynamics deprived of any characteristic microscopic time, meaning that the emission is governed by interactions at larger length scales.[1]LD Carlos, V de Zea Bermudez, VS Amaral, SC Nunes, NJO Silva, RA Sá Ferreira, J Rocha, CV Santilli, D Ostrovskii, Adv. Mater., accepted
5:15 PM - BB2.9
Block Copolymer Film with Sponge-Like Nanoporous Structure for Antireflection Coating
Wonchul Joo 1 , Min Soo Park 1 , Jin Kon Kim 1
1 Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk, Korea (the Republic of)
Show Abstract Porous thin films have been extensively employed for optical and electrical devices. Especially antireflection coating, which reduces light reflection at the transmittable substrate, is good application part of porous film. For antireflection coating, nanoporous structure is required. Thus nanoporous block copolymer (BCP) films can be used as an good antireflection coating because the refractive index (n) decreases with an increase amount of pores generated by the selective removal of one block in the block copolymer. BCP exhibits various microdomains with 10~50nm. Once these microdomains are selectively removed by UV exposure or ozone treatment, a porous structure is generated. After spin coating of Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA), the BCP film showed phase separation in short range due to large ΧN value even though annealing at high temperature was not taken. When UV light is irradiated to the film, PMMA was degraded by radical reaction whereas PS was crosslinked. Thus porous structure in tens of nano meters was prepared after selective solvent rinsing. When PMMA volume fraction was 0.69 in BCP, the films showed nearly 0% of reflectance with various thicknesses. The film was characterized Characteristic Matrix Theory and it showed almost 1.20 of n for all films.
BB3: Poster Session: Hybrid Functional Materials for Optical Applications
Session Chairs
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - BB3.1
Infrared Frequency Up-conversion in MEH-PPV.
Daniel Correa 1 , Leonardo De Boni 1 , Debora Balogh 1 , Cleber Mendonca 1
1 Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
Show Abstract9:00 PM - BB3.10
Nonlinear Optical Dispersion and Optical Limiting Properties of Au Metal-nanoparticles Dispersed SiO2 Composite Film.
Kyeong-Seok Lee 1 , Sung-Hoon Cho 2 , Soonil Lee 2 , Taek-Sung Lee 1 , Won-Mok Kim 1
1 Thin Film Materials Research Center, Korea Insitute of Science and Technology, Seoul Korea (the Republic of), 2 Department of Molecular Science and Technology, Ajou University, Suwon Korea (the Republic of)
Show Abstract9:00 PM - BB3.11
WITHDRAWN 03/19/07 Organic/Inorganic Hybrid Glasses Doped with (Erbium-ions/CdSe) Nanoparticles for Laser Amplifications
Kyung Choi 1
1 , Bell Labs, Lucent Technologies, Murray Hill, New Jersey, United States
Show AbstractTuesday, April 10Withdrawn-posterBB3.11
9:00 PM - BB3.12
Platinum Acetylide Oligomers as Nonlinear Absorbing Materials
Kye-Young Kim 1 , John Peak 1 , Kirk Schanze 1
1 Department of Chemistry, University of Florida, Gainesville, Florida, United States
Show AbstractWe have explored the properties of triplet excited states in a series of platinum acetylide oligomers of the type [trans-Pt(PBu3)2(-CC-Ar)2], where Ar is a highly conjugated two-photon absorbing organic chromophore. Incorporation of two-photon absorbers into a pi-conjugated system produces short-lived excited states (fs/ps) with high efficiency. Platinum acetylide units introduce strong spin-orbit coupling into the pi-conjugated system to give rise to high yields of long-lived triplet excited states (ns/us) having large triplet-triplet absorption cross sections. Thus, a platinum acetylide having two-photon absorbers will, in principle, feature a strong non-linear absorption in broad time domain. The presentation will focus on (1) the synthesis and photophysical characterization under one- and two-photon excitation, (2) the effect of two-photon absorbing chromophores on nonlinear absorption properties of platinum acetylides and (3) the evidence for reverse saturable absorption.
9:00 PM - BB3.13
Multimaterial Fibers with Optical and Optoelectronic Functionalities.
Nicholas Orf 1 , Yoel Fink 1
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractUntil recently, electronic and optoelectronic device processing has remained incompatible with much simpler thermal drawing techniques used in optical fiber production. The development of omnidirectional reflecting photonic bandgap fibers and optoelectronic photodetecting fibers composed of metals, polymer insulators, and amorphous chalcogenide semiconductors have reversed this paradigm. This achievement makes it possible to introduce semiconductor device functionalities at fiber-optic length scales, uniformity and cost. I will review the processsing of these fibers which require nanometer feature sizes be maintained over tens to hundreds of meters of fiber and show how higher-order functionality may be introduced on the fiber and system level. New fiber devices such as the first transverse surface emitting fiber laser and thin film photodetector fibers, among others, will illustrate additional functionalities that may be integrated into fibers. System-level integration of fiber device will be demonstrated with fiber arrays and fabrics that can detect the direction and location of incident illumination
9:00 PM - BB3.14
Non-radiative decay processes in Er3+ organic complexes.
Angelo Monguzzi 1 , Francesco Meinardi 1 , Riccardo Tubino 1
1 Dipartimento di Scienze dei Materiali, Università Milano Bicocca, Milano, MI, Italy
Show AbstractNew light sources in the near infrared (NIR) are requested in the field of telecommunications, especially to develop amplifiers for Local Area Networks. Organic Er3+ complexes have been recently proposed as a promising alternative to the well known silica-based systems. Devices based on these molecules show many advantages in respect to the traditional ones and should allow to realize compact and cheap optical amplifiers, possibly also by using electric excitation. Although a large number of complexes exhibiting NIR emission at 1.5 μm has been synthesized, expectations to obtain high efficiency emitters have been not fulfilled. This is due to the non-radiative de-excitation mechanisms which are more efficient in Er3+organic complexes than in inorganic matrix. Deep knowledge and exact evaluation of these processes are necessary to design proper chemical modifications aimed at directing the chemical design towards more efficient systems. In this work we have developed a model for the non radiative de-excitation of Er3+ ions in organic complexes based on the energy transfer process between the 4I13/2-4I15/2 transition of Er3+and C-H stretching overtones. According to the Förster’s theory of dipole-dipole interactions, the transfer rate is determined by the distance between donors (Er3+) and acceptors (C-H bonds), and by the spectral overlap between the corresponding electronic and vibrational levels. These quantities have been evaluated for the Er3Q9 [Erbium(III)tris(8-hydroxyquinoline)]. The lifetime of excited level 4I13/2, calculated by considering the transfer rate towards all the 18 C-H groups of the ligand (1.8 μs), is in perfect agreement with the experimental value, and it is 3 order of magnitude shorter than the radiative lifetime of this level. This finding demonstrate the validity of the model used and that the quenching is entirely produced by to the presence of C-H groups of the ligand. However, to significantly enhance the efficiency of these complexes is not sufficient to remove the C-H groups in the Er3+ first coordination sphere since the transfer rate from Er3+ to more distant C-H groups is of the same order of magnitude of the transfer to the first shell. Our results suggest that only by surrounding erbium with a low vibrational environment , for example by complete halogenation of the complex, it is possible to prepare efficient IR emitters with potential interesting applications in the field of plastic optical amplifiers.
9:00 PM - BB3.15
Electrochromic Fluorescent Cell by the Combination of Electrochromic Viologen and a 9-methylanthracene Polymer.
Eunkyoung Kim 1 , Yuna Kim 1 , Krishnamurthy Rameshbabu 1
1 Chemical Engineering, Yonsei University , Seoul Korea (the Republic of)
Show Abstract9:00 PM - BB3.16
High contrast ratio, durability and scalability of PProDOT-Me2 and V2O5-TiO2 composite based electrochromic windows(ECWs)
Sooyeun Kim 1 , Minoru Taya 1 2 , Chunye Xu 2
1 Materials Science & Engineering, University of Washington, Seattle, Washington, United States, 2 Mechanical engineering, University of Washington, Seattle, Washington, United States
Show Abstract9:00 PM - BB3.2
Two-photon Absorption and Optical Storage in a PolythiopheneFunctionalized with Azodye Pendants.
Daniel Correa 1 , Marcos Cardoso 1 , Vanessa Goncalves 1 , Debora Balogh 1 , Leonardo De Boni 1 , Cleber Mendonca 1
1 Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
Show Abstract9:00 PM - BB3.4
Ni Coordination in Alkali Gallium Silicate Glass-ceramics.
Nan Jiang 1 , Botao Wu 2 , Jianrong Qiu 3
1 Physics, Arizona State University, Tempe, Arizona, United States, 2 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai China, 3 State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
Show Abstract9:00 PM - BB3.5
Effect of Growth Temperature on the Characteristics of ZnO Films Grown on Si(111) Substrates by Metal-organic Chemical Vapor Deposition.
Zhu Junjie 1 , Yao Ran 2 , Fu Zhuxi 2 , Lee InHwan 1
1 School of Advanced Materials Engineering and Research Center of Industrial Technology, Chonbuk National University, Jeonju, Chonyu, Korea (the Republic of), 2 physics, University of Science and Technology of China, Hefei, Anhui, China
Show Abstract9:00 PM - BB3.6
Synchrotron Topographic Study of MgO Doped Czochralski-grown Near-stoichiometric LiNbO3.
G. Lei 1 2
1 Department of Mathematics and Physics, China University of Petroleum, BeiJing, Beijing, China, 2 , State Key Laboratory of Crystal materials, Shandong University, Jinan, Shandong, China
Show Abstract9:00 PM - BB3.7
Triplet Excimer Formation in Platinum Acetylides.
Jonathan Slagle 1 2 , Thomas Cooper 1 , Douglas Krein 1 3 , Joy Rogers 1 4 , Daniel McLean 1 5 , Augustine Urbas 1
1 Materials and Manufacturing Directorate, Air Force Research Labortory, Wright Patterson Air Force Base, Ohio, United States, 2 , AT&T Government Solutions, Inc., Dayton, Ohio, United States, 3 , Anteon, Inc., Dayton, Ohio, United States, 4 , UES, Inc., Dayton, Ohio, United States, 5 , Science Applications International Corporation, Dayton, Ohio, United States
Show AbstractTo prove the source of ground state self-quenching in trans-Pt(POct3)2(C≡CC6H4C≡CC6H5)2 is a result of triplet excimer formation, we carried out nanosecond transient absorption measurements on multiple concentrations. We also measured the ground state UV-vis absorption and emission from the samples. By constructing a kinetic model for the system we were able to determine rate constants for the formation and decay of the triplet excimer, 4.7 x 106 M-1s-1 and 6.9 x 105 s-1 respectively. We were also able to determine the transient absorption spectrum for the excimer which has an extinction coefficient maximum of 95,680 M-1cm1 at 600nm. Ground state absorption showed no evidence of aggregation and there was no emission present from the excimer. The formation of the excimer has been compared to the cross quenching of trans-Pt(POct3)2(C≡CC6H4C≡CC6H5)2 with the ligand HC≡CC6H4C≡CC6H5. In which case the cross quenching is faster by over one order of magnitude. This suggests that the formation of the triplet excimer is largely due to ligand to ligand interaction. Transient absorption spectral comparison shows that the excimer has decreased conformational mobility which is evident in the narrowing of the absorption band.
9:00 PM - BB3.8
Synthesis and Properties of New Phthalocyanines Bearing Electron-withdrawing or Electron-donating Groups.
Weijie Su 2 1 , Doug Krein 2 3 , Joy Rogers 2 4 , Jonathan Slagle 2 1 , Augustine Urbas 2
2 , Air Force Research Lab, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio, United States, 1 , AT&T government Solution, Inc, Fairborn, Ohio, United States, 3 , General Dynamics, Dayton, Ohio, United States, 4 , UES, Inc., Dayton, Ohio, United States
Show Abstract9:00 PM - BB3.9
Synthesis and Investigation of New Porphyrins with Electron-donating or Electron-withdrawing Groups.
Doug Krein 3 1 , Weijie Su 3 2 , Joy Rogers 3 4 , Jonathan Slagle 3 2 , Augustine Urbas 3
3 , Air Force Research Lab, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio, United States, 1 , General Dynamics, Dayton, Ohio, United States, 2 , AT&T Government Solutions, Inc, Fairborn, Ohio, United States, 4 , UES, Inc., Dayton, Ohio, United States
Show Abstract
Symposium Organizers
Alexander Cartwright State University of New York-Buffalo
Thomas M. Cooper Air Force Research Laboratory
Anna Koehler University of Potsdam
Kirk S. Schanze University of Florida
BB4: Organic-inorganic Hybrid Materials for Light-emitting Applications
Session Chairs
Wednesday AM, April 11, 2007
Room 2020 (Moscone West)
10:00 AM - **BB4.1
Harnessing the Triplet in Conjugated Polymer LEDs
Andrew Holmes 1 3 , Robert Borthwick 1 , Khai Leok Chan 2 1 , Sung Yong Cho 2 1 , Aedan Cosgriff 1 , Nicholas Evans 2 , Andrew Grimsdale 1 , Georgia McCluskey 1 , Scott Watkins 1 , Charlotte Williams 3
1 Bio21 Institute, University of Melbourne, Parkville, , Victoria, Australia, 3 Chemistry, Imperial College, London United Kingdom, 2 Melville Laboratory, University of Cambridge, Cambridge United Kingdom
Show AbstractIn recent years there has been much attention to harnessing the triplet energy resulting from electron-hole recombination in organic LEDs. Pioneering work by the Princeton-USC group has introduced the concept of using tris-cyclometallated iridium complexes as phosphorescent guests in small molecule devices. In the case of polymer LEDs fabricated by deposition from solution the opportunity exists to consider either blending the guest molecule in the polymer host or making a covalent attachment to the polymer chain. In this presentation the approaches of covalent attachment of the ligand to the polymer host, either conjugatively or non-conjugatively, will be compared and contrasted. Progress on design of new high energy polymer hosts will be reported. Finally, some consideration will be given to the formation of ketone defects in polyfluorene-based polymer LEDs.
10:30 AM - **BB4.2
Luminescent Metal-Based Molecular Materials – From Fundamentals To Functions.
Vivian Yam 1
1 Department of Chemistry, The University of Hong Kong, Hong Kong Hong Kong
Show AbstractRecent works in our laboratory have shown that novel luminescent metal-based molecular materials could be assembled through the use of various metal-ligand building blocks. In this presentation, various design and synthetic strategies together with the successful isolation of new classes of complexes of selected metals will be described. A number of these complexes have been structurally characterized and shown to display rich luminescence behaviour. The luminescence properties have been studied and their emissive origins elucidated. Correlations of the luminescence behaviour with the electronic and structural effects of the metal complexes have also been made. Different approaches and assembly motifs have been employed to tune the absorption and emission characteristics of these materials based on an understanding of their spectroscopic origins. Subtle changes in the microenvironment have been found to lead to drastic changes in both the electronic absorption and emission properties of some of these complexes. Through rational design and assembly strategies based on various coordination motifs and weak non-covalent metallophilic and π-π interactions that would lead to changes in the absorption and emission characteristics, these molecular materials may find potential applications and functions as triplet light-emitting materials, optical chemosensors, molecular optoelectronics, switches and optical memories.
11:30 AM - BB4.3
Self Organized Mesostructured Silica/Semiconducting Polymer Nanoccomposites and Their Integration into Opto-Electronic Applications.
Saar Kirmayer 1 , Ekaterina Dovgolevsky 1 , Michael Kalina 1 , Gitti Frey 1
1 Materials Engineering, Technion - Israel Institute of Technology, Haifa Israel
Show AbstractThe performance of semiconducting polymer optoelectronic devices depends crucially on polymer chain morphology and chain-chain interactions. Encapsulation of the semiconducting polymers into an ordered inorganic matrix can provide control over the polymer morphology and hierarchical structure, in combination with improving the environmental and chemical stability. Positioning polymer chains into the pores of an inorganic host, however, is challenging because organic hydrophobic species are not compatible with the aqueous sol-gel process conventionally used for the preparation of mesoporous ceramic hosts. Here we show that semiconducting polymer-incorporated lamellar, hexagonal, rhombohedral or cubic mesotructured silica can be prepared trough the use of micro-emulsions, sol-gel chemistry, and surfactant self-organization. The nanocomposite hierarchical structure is characterized using SAXS and TEM, while the optical properties of the polymer, being sensitive to its arrangement and environment, are used as in-situ probes to study the morphology of the confined polymer chains. Finally, The 3D continuous through-film conductive pathway provided by the rhombohedral and cubic phases has allowed the integration of ordered semiconducting polymer/silica nanocomposites into opto-electronic devices. The approach presented here for the preparation of optically responsive semiconducting polymer-incorporated mesostructured inorganic host matrices is expected to be general and extendable to other hybrid material compositions and structures.
11:45 AM - BB4.4
The Mechanism of Operation of Hybrid Organic/Colloidal Quantum Dot Light Emitting Devices.
Polina Anikeeva 1 3 , Jonathan Halpert 2 , Moungi Bawendi 2 , Vladimir Bulović 1
1 Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 3 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractWe investigate the mechanism of operation of the hybrid organic/colloidal quantum dot (QD) light emitting devices (QD-LEDs). By varying the position of the emitting QD monolayer within the stacked organic structure, we find that the quantum efficiency of the device improves by >50% upon imbedding the emissive QD monolayer into the hole-transporting layer <10 nm below the interface between hole and electron transporting layers. We consider two possible mechanisms responsible for this improvement, one based on the charge injection model of the device operation and the other based on the exciton energy transfer mechanism. In order to test our hypotheses we fabricate a set of structures that enable precise control of charge injection into colloidal QDs and allow us to differentiate contributions of the two processes.
12:00 PM - **BB4.5
Templated Nanoporous Materials for Optical and Electronic Applications.
Sarah Tolbert 1
1 Chemistry and Biochemistry, UCLA, Los Angeles, California, United States
Show Abstract12:30 PM - BB4.6
Energy Transfer Processes in Hybrid Organic-Inorganic Nanocomposites
Carsten Dosche 1 , Eyal Aharon 2 , Gitti Frey 2 , Patrick Parkinson 3 , Laura Herz 3 , Anna Koehler 1
1 Institute of Physics, University of Potsdam, Potsdam Germany, 2 Department of Materials Engineering, Technion, Haifa Israel, 3 Clarendon Laboratory, University of Oxford, Oxford United Kingdom
Show Abstract12:45 PM - BB4.7
New Light from Hybrid Inorganic-Organic Emitters.
Colin Belton 1 , Grigorios Itskos 1 , George Heliotis 1 , Pavlos Lagoudakis 2 3 , Martin Dawson 4 , Ian Watson 4 , Jochen Feldmann 3 , Ray Murray 1 , Donal Bradley 1
1 Physics, Imperial College London, London United Kingdom, 2 School of Physics and Astronomy, University of Southampton, Southampton United Kingdom, 3 Department of Phyics and CeNS, Ludwig-Maximilians Universität, Munich Germany, 4 Institute of Photonics, University of Strathclyde, Glasgow United Kingdom
Show AbstractHybrid inorganic/organic semiconductor structures offer the prospect of new devices that can combine the excellent electrical conductivity of inorganic materials with the attractive luminescence properties of organic materials. Consequently, devices based on dipole-dipole energy transfer from inorganic semiconductors to conjugated polymers can produce highly efficient emission across the entire visible spectrum.
We have investigated hybrid structures containing InGaN/GaN single quantum wells (QWs) that are spaced from fluorene-based polymer films by thin cap layers of GaN. Provided their electronic states are matched [1, 2], the close proximity of the polymer film to the QW promotes efficient non-radiative (Forster) energy transfer, resulting in a strong visible emission from the hybrid devices. We have also prepared hybrid structures where white light emission is obtained due to energy transfer from the InGaN/GaN QW to a blend of polyfluorene emitters.
Temperature-dependent spectrally-resolved measurements show that the non-radiative energy transfer from the QW to the polyfluorene film results in a significant enhancement in the organic emission, with as much as a twenty-fold increase over that resulting from simple radiative energy transfer [3]. Control measurements (without the QW) verify that the intensity enhancement is due to energy transfer from the UV-light emitting QW rather than any other effect related to the polymer/GaN cap layer interface. Time-resolved experiments show a significant reduction in the QW decay time providing further insight into the non-radiative nature of the transfer.
Spectrally-resolved measurements show that energy transfer can also occur to polymer blends that have been designed for white light emission. We find, however, that there are changes in the emission of the polymer blend excited via the quantum well compared to the same blend directly excited on glass. Microscopic studies have been used to examine this difference.
[1] D. Basko, G.C. La Rocca, F. Bassani and V.M. Agranovich, Eur. Phys. J. B 8, 353, (1999)
[2] Š. Kos, M. Achermann, V.I. Klimov and D.L. Smith, Phys. Rev. B, 71, 205309, (2005)
[3] G. Heliotis, G. Itskos, R. Murray, M.D. Dawson, I.M. Watson and D.D.C. Bradley, Adv. Materials 18, 334, (2006)
BB5: Charge and Energy Transfer in Organic-inorganic Hybrid Materials
Session Chairs
Wednesday PM, April 11, 2007
Room 2020 (Moscone West)
2:45 PM - BB5.1
Electrical Control of Forster Energy Transfer.
Klaus Becker 1 , John Lupton 1 2 , Josef Mueller 1 , Andrey Rogach 1 , Dmitri Talapin 3 4 , Horst Weller 4 , Jochen Feldmann 1
1 Photonics and Optoelectronics Group, Physics and CeNS, Ludwig-Maximilians-University, Munich Germany, 2 Department of Physics, University of Utah, Salt Lake City, Utah, United States, 3 The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 4 Institute of Physical Chemistry, University of Hamburg, Hamburg Germany
Show AbstractBringing together compounds of intrinsically different properties such as inorganic nanostructures and organic molecules constitutes a particularly powerful route to creating novel synergetic functionalities found in neither of the constituents. We introduce nanophotonic elements combining two classes of materials, elongated semiconductor nanocrystals and organic dyes. The physical nature of these elements combines the properties of the individual components to yield new features. The large absorption cross section of the nanocrystals provides an efficient route to concentrating excitation energy and photopumping dye molecules with much weaker absorptions. This results in an antenna pathway for excitation [1]. The efficiency of this energy transfer depends on the degree of spectral overlap between donor emission and acceptor absorption of the single nanocrystal and dye molecule, respectively. As the CdSe/CdS nanorods employed exhibit a large quantum confined Stark effect (QCSE) [1-3], it becomes possible to electrically control the spectral resonance between a single nanocrystal and a single adjacent dye molecule. This fine tuning of the electronic properties allows to directly control the efficiency of energy transfer [1]. Thus, with this far-field manipulation of a near-field phenomenon by a remote electric field, the emission from single dye molecules can be controlled electrically [1]. Such a device constitutes a novel single molecule switch. Interestingly, the efficiency of energy transfer in natural and synthetic light-harvesting systems is generally limited by energetic disorder between different chromophores. As a result, a macroscopic description of energy transfer rates in inhomogeneously broadened ensembles may be misleading. Electrically tailoring the spectral overlap of the optical transition of a single donor and a single acceptor highlights the role of the individual homogeneous transitions in energy transfer. This offers a route to a deeper microscopic understanding of the nature of energy transfer in energetically disordered systems.[1] K. Becker et al., Nature Mat. 5, 777 (2006).[2] J. Müller et al., Nano Lett. 5, 2044 (2005).[3] J. Müller et al., Phys. Rev. Lett. 93, 167402 (2004).
3:00 PM - **BB5.2
Dye Sensitized Solar Cells: New Photoelectrode Architectures
Joseph Hupp 1 , Alex Martinson 1 2 , Jeff Elam 2 , Michael Pellin 2
1 Chemistry, Northwestern University, Evanston, Illinois, United States, 2 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractThe best existing dye-sensitized solar cells are based on high-area sintered nanoparticle aggregates. The nanoparticles facilitate light collection but are characterized by poor electron transport dynamics -- a shortcoming that unfavorably affects both photocurrents and photovoltages. This talk will describe new photoelectrode geometries that allow for much more rapid transport. Indeed, direct measurements of transport with fully operational cells reveal that some geometries can increase the dynamics by more than two orders of magnitude while simulataneously inhibing the dynamics of charge recombination
3:30 PM - **BB5.3
Redox Chemistry of “Hot” Electrons at Sensitized TiO2 Interfaces.
Gerald Meyer 1 2 , Aaron Staniszewski 1 , Shane Ardo 1
1 Chemistry, Johns Hopkins, Baltimore, Maryland, United States, 2 Materials Science and Engineering, Johns Hopkins, Baltimore, Maryland, United States
Show Abstract4:30 PM - BB5.4
Bio/Electronic Hybrid Materials for Interchromophore Distance and Orientation Control.
Onur Kas 1 , Manoj Charati 1 , Kristi Kiick 1 , Mary Galvin 2
1 Materials Science and Engineering, University of Delaware, Newark, Delaware, United States, 2 , Air Products and Chemicals, Allentown, Pennsylvania, United States
Show AbstractThe performance of organic semiconductor devices depends strongly on the intermolecular interactions between the electroactive molecules. In order to probe the changes in these interactions with respect to intermolecular distance and orientation we have designed helical peptide templates that can display chromophores as side chains of non-natural amino acids. Via the use of these bio/electronic hybrid templates, chromophores of choice can be placed on the same side of the helix with a 6Å spacing or with an 11Å spacing. Alternatively, they can be placed on opposite sides of the helical peptide backbone. Our previous NMR, optical and photophysical studies of peptides modified with methylstilbene sidechains, conducted in solution, proved that use of the 6Å spacing template permits investigation of excimer formation and ground state interactions. Use of the 11Å and/or opposite placement template avoids electroactive sidechain aggregation, and therefore, electronic interactions. These templates are currently being used for controlling the spacing and orientation between oxadiazole containing poly(p-phenylenevinylene) (OXA-PPV) oligomers. These new hybrid materials have a high tendency to crystallize as compared to their neat peptide template counterparts. This presentation will outline how OXA-PPV oligomers photophysically interact when presented with different intermolecular distances and orientations on the peptide templates. The results will be compared to those from the previous studies on peptides modified with methylstilbene sidechains.
4:45 PM - **BB5.5
Hybrid Solar Cells based on ZnO and a Conjugated Polymer.
Rene Janssen 1 , Waldo Beek 1 , Martijn Wienk 1
1 Molecular Materials and Nanosystems, Eindhoven University of Technology, Eindhoven Netherlands
Show Abstract5:15 PM - BB5.6
Electroactive Materials for High Efficiency OLEDs: Charge Transporting Oligomers and Phosphorescent Polymers.
Scott Watkins 1 2 3 , Andrew Holmes 2 1 3 , Khai Leok Chan 3 2 , Sung Yong Cho 3 2 , Nick Evans 3 , Georgia McCluskey 2 1 , Robert Borthwick 2 , Aedan Cosgriff 2 , Chris Mak 3
1 Molecular and Health Technologies, CSIRO, Melbourne, Victoria, Australia, 2 School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia, 3 Melville Laboratory, Department of Chemistry, University of Cambridge, Cambridge United Kingdom
Show Abstract5:30 PM - **BB5.7
Heavy Metal Complexes for Efficient Electrophosphorescence
Mark Thompson 1
1 Department of Chemistry, University of Southern California, Los Angeles, California, United States
Show AbstractThere has been a great deal of interest in developing new materials for the fabrication of light emitting diodes (OLEDs). We have prepared a range of intensely luminescent Ir(III) and Pt(III) complexes, which have found application in both monochromatic and white OLEDs. The key issue here is the interplay between the ligand based and MLCT excited states. The former is largely involved in tuning the emission color, while the later is critical for achieving efficient phosphorescent emission at room temperature. Through careful design of ligands and metal complexes, we have achieved efficient electroluminescence, ranging form the near-UV into the near-IR. A model will be presented for the excited states in these phosphorescent emitting materials and the strategies for efficient color tuning throughout the visible spectrum will be discussed. I will focus my attention in this talk on our efforts to achieve high efficiency for both high energy (near-UV to blue) and low energy (near-IR) emission. These studies involve both new materials and novel device architectures to achieve high efficiencies.
Symposium Organizers
Alexander Cartwright State University of New York-Buffalo
Thomas M. Cooper Air Force Research Laboratory
Anna Koehler University of Potsdam
Kirk S. Schanze University of Florida
BB6: Hybrid Composites for Optical Applications
Session Chairs
Thursday AM, April 12, 2007
Room 2020 (Moscone West)
9:30 AM - BB6.1
Optical Properties of CdSe/ZnSe Nanoparticles Incorporated into Tethered Thermoresponsive N-Isopropylacrylamide Hydrogel Thin Films.
Beinn Muir 1 , Yun Zong 2 , Cathrin Corten 3 , Dirk Kuckling 3 , Wolfgang Knoll 4 1 , Curtis Frank 1
1 Chemical Engineering, Stanford University, Stanford, California, United States, 2 , Institute of Materials Research and Engineering, Research Link Singapore, 3 , Fachrichtung für Chemie und Lebensmittelchemie, Dresden Germany, 4 Materials Science, Max Planck Institute for Polymer Research, Mainz Germany
Show AbstractSemiconductor quantum dots (QDs) are highly luminescent nanocrystals that exhibit narrow emission wavelengths tunable by changing the nanoparticle diameter and elemental components. Incorporation of QDs into a cross-linked hydrophilic polymer matrix forms an optically active scaffold. The QDs can be attached to the polymer matrix through hydrogen bonding, covalent bonding to the preformed polymer matrix, and/or in-situ gelation using the QDs as a cross-linking agent. The polymer matrix can be selected such that it undergoes rapid volume changes to external stimuli gradients such as temperature or pH, due to a balance between polymer elastic energy and osmotic pressure, and on collapse the polymer network becomes heterogeneous with localised polymer-rich hydrophobic regions. For surface-confined thin films, volume changes are known to occur in the millisecond regime, a timescale ideal for actuator and sensor applications. Within a collapsed film QDs covalently bound to the polymer matrix will become close packed in the polymer-rich regions. This results in a change in the optical properties due to the close proximity of individual nanoparticles. Incorporation of a suitable fluorescent probe can be used to act as the acceptor in a fluorescence resonance energy transfer (FRET) pair. The importance of these hydrogel-nanoparticle hybrid materials is twofold, (i) utilization of the QD emission in biosensing configurations, and (ii) characterization of the polymer matrix and cross-link junction dynamics through the use of optical techniques such as surface plasmon resonance (SPR), surface plasmon fluorescence spectroscopy (SPFS), confocal microscopy and fluorescence correlation spectroscopy (FCS). Here we report the incorporation of CdSe/ZnSe semiconductor QDs into temperature sensitive N-isopropylacrylamide copolymer thin films, and the analysis of the material's optical properties as a function of polymer conformation for thin tethered films.
9:45 AM - BB6.2
Synthesis and Passivation of Silicon Nanocrystals Produced in a Non-Thermal Plasma Reactor
Lorenzo Mangolini 1 , Uwe Kortshagen 1
1 Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractSince the discovery of visible photoluminescence from porous silicon (Furukawa and Miyasato,1988;Canham,1990), intense research has concentrated on silicon nanostructures. With respect of II-VI semiconductor quantum dots, silicon is cheap and abundant, and it is generally accepted as a non-toxic material. Silicon quantum dots with efficient optical properties could find application for OLEDs, photovoltaic devices, biological tagging, and optical interconnect in the semiconductor industry, where the compatibility of the material with the current semiconductor technology presents another significant advantage.In this work, a non-thermal plasma system is used for the synthesis of silicon quantum dots. This approach presents many advantages with respect of other synthetic techniques, such as liquid phase reactions and other gas phase system. Charging of the particles in the plasma quenches agglomeration and allows to obtain small particles with a rather monodispersed size distribution. Mass yield as high as 50 mg/hour have been achieved (Mangolini, et al.,2005), and the produced particles also show high crystalline fraction. A first attempt to shed light into the process of formation of very small crystals in a plasma will be presented. The exact evolution of particle structure during the growth is not yet understood, but the particle temperature cycle in the discharge has been modelled. It is found that very small particles (<5nm) do not have a steady temperature, and that their instantaneous temperature can largely exceed the background gas temperature. A single argon ion – electron recombination event releases a significant amount of energy (15.76 eV), which leads to a steep increase in the particle temperature. Moreover, the presence of free radicals in the discharge, such as atomic hydrogen, also contributes to the particle heating. Temperature fluctuations are a good candidate to explain the formation of very small crystalline particles.Following the extensive work that can be found in the literature on the alkylation of silicon surfaces (Buriak,2002), the plasma produced particles were reacted with various alkenes, and the optical properties of the resulting silicon ink were characterized. For particles emitting in the near infrared, ensemble quantum yields between 60% and 70% have been achieved with excellent reproducibility (Jurbergs, et al.,2006;Mangolini, et al.,2006). To our knowledge these quantum yields are among the highest reported for silicon quantum dots. The properties of the alkylated silicon nanocrystals, such as their sensitivity to the chemical environment, will be discussed, and a new approach for a quick and efficient grafting of the silicon nanoparticle surface with organic molecules will be presented.This work was supported primarily by NSF under grant DMI-0556163. Partial support was also provided by the MRSEC Program of the National Science Foundation under Award Number DMR-212302.
10:00 AM - BB6.3
Thermo-optical Properties of Hybrid Nanocrystal Molecules in Ice and Water: Characterization of Heat Generation and Actuation.
Alyssa Thomas 1 , Hugh Richardson 1 , P. Gregory Van Patten 1 , Martin Kordesch 2 , Alexander Govorov 2
1 Chemistry and Biochemistry, Ohio University, Athens, Ohio, United States, 2 Physics and Astronomy, Ohio University, Athens, Ohio, United States
Show Abstract10:15 AM - BB6.4
Scanning Transmission Electron Microscopy in Transparent Glass-ceramics.
Nan Jiang 1 , Bo Tao Wu 2 , Shifeng Zhou 3 , Jianrong Qiu 3
1 Physics, Arizona State University, Tempe, Arizona, United States, 2 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai China, 3 State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
Show Abstract10:30 AM - BB6.5
Synthesis and Photoluminescence of Gold Nanoclusters Using Dendrimer Templates at Physiological Temperature.
Yuping Bao 1 , Chang Zhong 1 , Dung Vu 1 , R. Dyer 1 , Jeniffer Martinez 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractSingle-molecule manipulation and detection of biomolecules has significantly advanced our understanding of the molecular movement, dynamics, and biological function of proteins. Fluorescence microscopy currently serves as one of the primary noninvasive techniques for the sensitive detection of molecules in solution and on surfaces. However, the performance and sensitivity of this laser-induced fluorescence technique is strongly influenced by the fluorescent labels attached to DNA, proteins or cells. Organic dyes have most commonly been used as fluorescent biolabels; however, they quickly photobleach, limiting the time scale over which molecular events can be followed. Quantum dots show great promise for fluorescence measurements due to their improved photophysical properties, such as size-tunable narrow emissions, large Stokes shifts and minimal photobleaching. However, problems still exist for the use of quantum dots as biolabels, including: photoblinking, toxic synthetic approaches, surface passivation issues and relatively large physical sizes that are comparable to proteins. Here, we report the synthesis of a new class of fluorescent labels, gold nanoclusters, which consist of several gold atoms (<1 nm in size) with strong fluorescence emission. These small fluorescent gold nanoclusters are synthesized at physiological temperature using poly(amidoamine) dendrimer as a template. Small blue emissive gold nanoclusters were produced without the use of a reductant and without concurrent nanoparticle formation. Gold nanoclusters with green and red emissions were synthesized using a mild reductant, also without nanoparticle formation. The studies of pH-dependent stability suggest that these fluorescent nanoclusters are very stable in a pH range of 6 - 8. These new approaches produce gold nanoclusters with a much higher yield and eliminate the toxicity of the previously reported process, resulting in a biologically compliant approach. This work is the first known report of fluorescent gold nanoclusters via a green-chemistry approach and without the formation of gold nanoparticles. This work is funded by Los Alamos Laboratory Directed research and Development program.
10:45 AM - BB6.6
Exciton-photon Polaritons in Planar Microcavities Containing Perovskite Organic/inorganic Quantum Wells.
Antoine Brehier 1 , Radoslav Parashkov 1 , Jean-Sebastien Lauret 1 , Emmanuelle Deleporte 1 , Xavier Lafosse 2 , Sophie Bouchoule 2
1 , LPQM - ENS Cachan, Cachan France, 2 , LPN-CNRS, Marcoussis France
Show Abstract11:30 AM - BB6.7
Studies of KDP Crystals Doped with Potassium Dichromate using Inductively Coupled Plasma (ICP) and UV Spectrophotometer
Selemani Seif 1
1 Physics Department, Alabama A & M University, Huntsville, Alabama, United States
Show AbstractThis paper reports on absorption spectra observed on Potassium Diphosphate (KDP) crystals doped with Potassium Dichromate (PD). The Ultra Violent (UV) and Inductively Coupled Plasma (ICP) analysis of pure and doped KDP crystals showed significantly increased concentration of PD impurities into the grown crystals at 200-280 Nanometer range. This indicated that the presence of Potassium Dichromate ions in KDP crystals play a reformative role in UV spectral of KDP.
11:45 AM - BB6.8
Atomic-scale Structure of Hybrid Functional Nanomaterials.
Valeri Petkov 1
1 Physics, Central Michigan University, Mt. Pleasant, Michigan, United States
Show AbstractKnowledge about the three-dimensional atomic arrangement, including the chemical type & positions of atomic/molecular units in space, is an important prerequisite to understanding, predicting and improving properties of materials. With bulk crystals it is routinely obtained by Bragg x-ray diffraction. With hybrid functional nanomaterials, however, traditional crystallography fails because of the limited length of structural coherence and chemical inhomogeneity they show. We will present a non-traditional experimental approach involving high-energy x-ray diffraction and atomic Pair Distribution Function analysis for determining the atomic arrangement in hybrid functional nanomaterials with subangstroem resolution. The great potential of the approach will be illustrated with examples from recent studies on silver, platinum and gold/dendrimer composites used in optical and sensing applications
12:00 PM - BB6.9
Full Color Photorefractive Composites.
Tao Gu 1 , Peng Wang 1 , Shuji Rokutanda 1 , Michiharu Yamamoto 1 , Robert Norwood 2 , Nasser Peyghambarian 2
1 , Nitto Denko Technical Corporation, Oceanside, California, United States, 2 College of Optical Sciences, University of Arizona, Tucson, Arizona, United States
Show AbstractHigh performance photorefractive (PR) materials, sensitive to full color systems (blue (488 nm), green (532 nm) and red (633 nm) lasers), were developed based on a hole-transport TPD (tetraphenyldiphenyldiamine) type polyacrylate matrix. In these full color systems both an excellent photorefractive response and good transparency were achieved. The results for PR samples with a 50 um thickness exhibited high transparency (T532nm = 60 % to 80 %), large diffraction efficiency (80 ~ 90 %), fast response (< 10 ms), and good phase stability (at 60 °C over several months). Multiple wavelength operations were also achieved in these composites. These devices can be used as a stepping stone in the realization of all-color holographics, because of their sensitivity to the blue (488 nm), green (532 nm) and red (633 nm) wavelengths. This demonstrates that these devices have the potential advantage of performing as a dynamic full-color holographic recording medium.
12:15 PM - BB6.10
Exceptional Electro-Optic Properties Directed by the Self-Assembly and Click Chemistry of Organic Functional Materials
Tae-Dong Kim 1 , Jingdong Luo 1 , Sei-Hum Jang 1 , Jae-Won Ka 1 , Yen-Ju Cheng 1 , Xinghua Zhou 1 , Zhengwei Shi 1 , Steven Hau 1 , Brent Polishak 2 , Su Huang 1 , Alex Jen 1 2
1 Materials Science and Engineering, University of Washington, Seattle, Washington, United States, 2 Chemistry, University of Washington, Seattle, Washington, United States
Show AbstractPoled organic electro-optic (EO) materials have enabled many advances in the exploration of high-speed and broadband information technologies. Polymer based EO devices have been demonstrated to have large bandwidths over 110 GHz, low driving voltages, and sustain their performance in a flexible form or under extreme environmental conditions. For optical circuits, organic EO materials can be easily integrated with stripline- or ring-structured waveguides made of sol-gels, low-loss fluorinated polymers, silicon slots, conducting oxides, and photonic crystals. They have also been utilized for the generation/detection of a gap-free pulsed THz system with a bandwidth up to ~12 THz. A major breakthrough in the area of organic EO materials has been recently achieved. To go beyond the oriented gas model limit for organic EO materials, new approaches of using nanoscale architecture control and supramolecular self-assembly have been proved as a very effective method to create a new paradigm for materials with very exciting properties. High-performance EO polymers were demonstrated by a facile and reliable Diels-Alder “click” reaction for postfunctionalization and lattice hardening to improve EO activity and thermal stability. This type of “click” chemistry paves the way to systematically study the relationship among EO activity, chromophore shape, and number density of the chromophores. Reversible supramolecular interactions were also introduced to a new generation of EO dendrimers and polymers to create self-assembled nano-objects, overcome strong intermolecular electrostatic interaction, and improve their poling efficiency and stability. These self-organized EO materials were used as hosts in a binary chromophore system to further improve chromophore number density and r33 value. With these novel approaches, we succeeded in enlarging the full potential of organic NLO materials by a factor of 3~5 and developing a variety of nano-structured organic EO materials with ultrahigh r33 values (>350 pm/V at the wavelengths of 1310 and 1550 nm, more than 10 times that of LiNbO3) and excellent auxiliary property, such as thermal stability and optical transparency. The success of these material developments has inspired the exploration of new device concepts to take full advantage of organic EO materials with ultrahigh r33 values.
12:30 PM - BB6.11
Self-Patternable Amine-Functionalised Organic-Inorganic Hybrids For Integrated Optics Substrates.
R. Ferreira 1 2 , P. Andre 2 3 , R. Nogueira 3 , P. Marques 4 5 , E. Pecoraro 1 6 , L. Fu 1 , A. Macedo 1 , N. Silva 1 2 , C. Vicente 1 2 3 , S. Ribeiro 6 , L. Pellegrino 7 , P. Monteiro 7 , V. Bermudez 8 , L. Carlos 1 2
1 CICECO, Universidade de Aveiro, Aveiro Portugal, 2 Physics, University of Aveiro, Aveiro Portugal, 3 Telecommunications Institute, University of Aveiro, Aveiro Portugal, 4 Departamento de Física/ Faculdade de Ciências, Universidade do Porto, Porto Portugal, 5 Unidade de Optoelectrónica e Sistemas Electrónicos, INESC, Porto Portugal, 6 Instituto de Química, UNESP, Araraquara Brazil, 7 , Siemens SA, Alfragide Portugal, 8 , Departamento de Química and CQ-VR, Universidade de Trás-os-Montes e Alto Douro Portugal
Show Abstract12:45 PM - BB6.12
Fourier Transform Infrared Absorbance and Photoluminescence Spectroscopy Studies of Conducting Polymer/CdSe Colloidal Quantum Dot Nanocomposites for Application to Infrared Photodetectors.
Kevin Lantz 1 , Adrienne Stiff-Roberts 1
1 Electrical and Computer Engineering, Duke University, Durham, North Carolina, United States
Show AbstractBB7: Hybrid Nanoparticle Systems for Optical Applications
Session Chairs
Thursday PM, April 12, 2007
Room 2020 (Moscone West)
2:30 PM - **BB7.1
Tailoring the Plasmonic Properties of Metal Nanostructures through Shape-controlled Synthesis.
Younan Xia 1
1 Chemistry, University of Washington, Seattle, Washington, United States
Show Abstract3:00 PM - **BB7.2
Elastic and Inelastic (Raman) Scattering from Anisotropic Metal Nanoparticles.
Catherine Murphy 1
1 Dept of Chemistry, University of South Carolina, Columbia, South Carolina, United States
Show AbstractMetal nanoparticles are well-known to intensely absorb and scatter light in the visible and near-infrared region of the electromagnetic spectrum. The wavelengths of the absorbed and scattered light depend on nanoparticle material, local dielectric constant, and shape. In our laboratory we have been able to make gold and silver nanopartices in a variety of shapes with good control (various aspect ratio rods, cubes, hexagonal platelets, etc.). In this talk we will explore the shape dependence of the elastically scattered light from metal nanoparticles using darkfield microscopy, and we will also examine the shape dependence of inelastic light scattering, using surface-enhanced Raman spectroscopy. Chemical sensing and biological imaging applications that use these features of metal nanoparticles will be discussed.
3:30 PM - **BB7.3
Negative Index Materials in the Optical Range
Gennady Shvets 1 , Yaroslav Urzhumov 1 , Vitaliy Lomakin 2
1 Physics, The University of Texas at Austin, Austin, Texas, United States, 2 Electrical and Computer Engineering, The University of California at San Diego, La Jolla, California, United States
Show Abstract4:30 PM - BB7.4
Metallic Nanowire Optical Antennas.
Edward Barnard 1 , Mark Brongersma 1
1 , Stanford University, Stanford, California, United States
Show AbstractA combined near-field and far-field study of the optical properties of metallic nanowire antennas is presented. These wires support resonant, surface plasmon excitations that enable concentration of light into deep sub-wavelength volumes. We have produced 50 nm diameter silver and gold nanowires of varying length using a template-assisted electrochemical process. We also have fabricated segmented wires with alternating Au and Ag regions using the same technique. After growth the template was dissolved and the nanowire suspension was then spun onto a glass substrate for optical characterization. The segmented wires were also used to generate antenna structures with nanoscale feed gaps by selectively etching away one of the metals.The size dependent optical properties of the wires were investigated using a dark-field optical microscope. Near-field scanning optical microscope (NSOM) images clearly show an electromagnetic field concentration near the antenna surface and in the feed gap. The optical images were compared to full-field electromagnetic simulations. The results of this study could impact the design of templates for surface enhanced Raman and non-linear spectroscopy as well as the work on nanoscale photodetectors and emitters.
4:45 PM - BB7.5
Carbon Nanotubes as Optical Materials.
Shoaxin Lu 1 , Ye Liu 1 , Ning Shao 1 , Balaji Panchapakesan 1
1 Electrical Engineering, University of Delaware, Newark, Delaware, United States
Show Abstract5:00 PM - BB7.6
Metallic Nanoshell Arrays as Bifunctional Substrates for Integrated Surface Enhanced Raman/Infrared Absorption Spectroscopies
Hui Wang 1 2 , Janardan Kundu 1 2 , Fei Le 3 2 , Peter Nordlander 3 4 2 , Naomi Halas 1 4 2
1 Chemistry, Rice University, Houston, Texas, United States, 2 Laboratory for Nanophotonics, Rice University, Houston, Texas, United States, 3 Physics, Rice University, Houston, Texas, United States, 4 Electrical and Computer Engineering, Rice University, Houston, Texas, United States
Show AbstractSeveral important spectroscopic probes of molecules, such as Raman scattering, infrared vibrational spectroscopy, UV-vis, and fluorescence spectroscopy, can be significantly enhanced or modified in the direct vicinity of metallic nanostructures. The optical excitation of the plasmon resonances supported by metallic nanostructures gives rise to intense local electromagnetic fields, which are largely responsible for the observed spectroscopic enhancements and modifications. It has previously been shown that metal-based nanoparticles whose plasmon energy can be controlled and tuned by adjusting nanoparticle geometry can serve as optimized substrates for surface enhanced Raman scattering (SERS) in the near-IR region of the spectrum. Solid metallic nanoparticles fabricated with uniform nanoscale interparticle gap spacings also provide a geometry with strong SERS signals, by exploiting the large field intensities associated with the interparticle plasmons, or “hot spots” in a condensed geometry. The complementary vibrational probe, surface enhanced infrared absorption spectroscopy, or SEIRA, which involves the direct excitation of molecular vibrational resonances in the mid-IR region of the spectrum, has received far less relative attention than SERS. Here we show that by combining both geometries- by condensing tunable near IR resonant plasmonic nanoparticles into arrays with nanoscale gaps spacings- in a single substrate, both strong SERS and SEIRA enhancements can be accomplished simultaneously. We have developed a robust chemical self-assembly approach for the fabrication of Au nanoshell arrays with nanoscale interparticle gaps. By adjusting the concentration of the nanoshell solutions, monolayer, double layer, or multilayer nanoshell arrays can be selectively fabricated. The arrays prepared by this method possess well-defined plasmon resonances in near infrared and mid infrared spectral regions that arise from the plasmon coupling between adjacent nanoshells. The plasmon resonance frequencies of the nanoshell arrays can be systematically tuned by tailoring the core and shell dimensions of individual nanoshells. Both the far-field and near-field optical properties of the nanoshell arrays are simulated using numerical electrodynamic calculations (Finite Difference Time Domain method). The local field enhancements in the junctions between neighboring nanoshells provide the “hot-spots” which can be excited by either near-IR or mid-IR light, enhancing SERS and SEIRA simultaneously in the same precise locations on the substrate. The spectral features observed in the SEIRA spectra show highly asymmetric, Fano-type line shape characteristics, believed to be due to the interaction of the molecular vibrations with the electronic excitations in the metal.
5:15 PM - BB7.7
Metal Nanoparticle / Semiconductor Nanowire Hybrid Structures for Solar Energy Capture
Tyler Pounds 1 , M. Norton 1 , David McIlroy 2
1 School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington, United States, 2 Department of Physics, University of Idaho, Moscow, Idaho, United States
Show AbstractBroadband plasmonic absorption has been exhibited in Au nanoparticles deposited on GaN nanowires. Plasmonic excitation occurs at a specific resonance wavelength for each nanoparticle according to its size and shape. Thus, a broad range of absorption wavelengths can be obtained by carefully controlling the sizes and shapes of the Au nanoparticles. Unlike our previous work where we demonstrated noble metal/polymer hybrid systems with absorption characteristics matching the broad solar spectrum, in this present study we are using the absorption characteristics of noble metal nanoparticles formed onto semiconducting nanowires, which serve as the conduits for the transport of charge. GaN is particularly useful as the nanowire substrate because it is easy to grow and the transport properties can be enhanced via n-type doping. In this presentation, we will report on our work to control the particle size of the Au nanoparticles and to determine the effects of nanoparticle size, distribution, and concentration on the absorption of solar radiation. The Au nanoparticles are deposited onto mats of GaN nanowires by plasma enhanced chemical vapor deposition. The size of the nanoparticles can be varied (typically on the range 1-20nm) by changes of temperature and pressure during growth and multimodal size distributions are possible. We will also report on our latest attempts at using this hybrid system to create actual PV devices.
5:30 PM - BB7.8
Silver Nanoparticle Modified Fluorescence as a Function of Spectral Overlap.
Yeechi Chen 1 , Keiko Munechika 1 , David Ginger 1
1 Chemistry, University of Washington, Seattle, Washington, United States
Show Abstract5:45 PM - BB7.9
The Influence of Multilayer Plasmon Dispersion on Near-Field Focusing at Visible Frequencies
Pieter Kik 1 , Amitabh Ghoshal 1 , Grady Webb-Wood 1
1 CREOL/The College of Optics and Photonics, University of Central Florida, Orlando, Florida, United States
Show AbstractThe recent progress in negative index media has been achieved by nanoscale control over the magnetic and electric response of artificial metallodielectric structures, leading to demonstrations of negative refraction and focusing at frequencies ranging from the microwave regime to the near-infrared. At short length scales, analogous effects can be observed in materials that only exhibit negative permittivity. It has been predicted that thin metal films can be used to generate images with a spatial resolution better than the diffraction limit via the local excitation of surface plasmons. Such near-field focusing could have applications in optical data storage and nanofabrication. Near-field scanning optical microscopy (NSOM) experiments will be presented that clearly demonstrate frequency dependent focusing using a near-field lens. The `perfect lens' was fabricated by depositing a 50nm thick gold layer onto a 50nm thick silicon nitride membrane. Focusing is detected by monitoring the interference between light emitted from a nanoscale object (the aperture of an NSOM tip) and radiation scattered by Pt nanoparticles placed in the image plane behind the lens. NSOM scans performed at wavelengths in the range 468nm-676nm reveal the role of surface plasmons in the imaging process. It is shown that the interference patterns observed match the surface plasmon dispersion relation of the free-standing material bilayer. It is demonstrated that the resolution of the near-field lens can be tuned by optimizing the relative thickness of the metal and dielectric layer. Experimental results will be compared with a dipole scattering model that takes into account the complete multilayer plasmon dispersion relation.