Nanoengineering of Light Absorption—From Hot Carriers to Photothermal Effects

In the last decade, optical nanoantennas have revolutionized light manipulation and control at the nanoscale. Light absorption was initially considered a purely detrimental process, reducing the efficiency of optoelectronic devices. Recently, however, it has attracted growing interest, enabling novel light-energy conversion pathways, such as hot carrier harnessing, but also interesting application opportunities based on nanoscale photothermal effects.<br/>In this talk, I will first present fundamental aspects of plasmonic hot carrier generation and collection towards photoelectrochemical devices for light energy storage. In particular, I will report the construction, optoelectronic and photoelectrochemical characterization of plasmon-driven devices that operate via hot-hole injection, and I will compare them to their hot electron counterparts [1-4]. I will also show emerging opportunities for plasmonic hot carriers in redox-couple based photoelectrochemical devices and advanced optical design strategies for improving the efficiency [5]. Overall, these results demonstrate the critical role of the metal properties onto hot carrier generation and transport. Thus, I will next report on our recent effort towards the synthesis of record-high aspect ratio gold monocrystalline flakes [6]. In particular, I will discuss how we can leverage them for understanding fundamental electronic processes in metals as well as plasmonic photo-electrochemistry. Finally, I will focus on collective photothermal effects in plasmonic networks and discuss a fast computational method we developed to estimate local temperature maxima and minima. I will conclude with an outlook on applications of hot carriers and photothermal effects in nanoengineered optical antennas.<br/><br/><b>References</b><br/>[1] G Tagliabue, AS Jermyn, R Sundararaman, AJ Welch, JS DuChene, R Pala, AR Davoyan, P Narang, HA Atwater, <i>Quantifying the role of surface plasmon excitation and hot carrier transport in plasmonic devices</i>, <b>Nature Communications 2018</b>, 9 (1), 3394.<br/>[2] G Tagliabue*, JS DuChene*, M Abdellah*, A Habib, DJ Gosztola, Y Hattori, WH Cheng, K Zheng, SE Canton, R Sundararaman, J Sá, HA Atwater, <i>Ultrafast hot-hole injection modifies hot-electron dynamics in Au/p-GaN heterostructures</i>, <b>Nature Materials 2020</b>, 19(12), 1312-1318. (* equal contribution)<br/>[3] JS DuChene*, G Tagliabue*, AJ Welch, WH Cheng, HA Atwater, <i>Hot Hole Collection and Photoelectrochemical CO2 Reduction with Plasmonic Au/p-GaN Photocathodes</i>, <b>Nano letters 2018</b>, 18 (4), 2545-2550 (* equal contribution)<br/>[4] G Tagliabue, JS DuChene, A Habib, R Sundararaman, HA Atwater – <i>Hot-Hole versus Hot-Electron Transport at Cu/GaN Heterojunction Interfaces</i> - <b>ACS Nano 2020</b>, 14, 5, 5788–5797.<br/>[5] F Kiani, F Sterl, TV Tsoulos, K Weber, H Giessen, G Tagliabue, <i>Ultra-Broadband and Omnidirectional Perfect Absorber Based on Copper Nanowire/Carbon Nanotube Hierarchical Structure</i>, <b>ACS Photonics 2020</b> 7 (2), 366-374, 2020<br/>[6] F Kiani, G Tagliabue, <i>High Aspect Ratio Au Microflakes via Gap-Assisted Synthesis</i>, <b>Chemistry of Materials 2022</b>, 34(3), 1278-1288.