Organic Small Molecule Based Emerging Applications in Opto Electronic

Organic conjugated small molecules are freely band gap tuning, low molecular weight to be available thermally deposited allowing semiconductor process, which have served as an important material for electronic devices today. Wavelength selectivity among absorption properties allowed for expansion with organic light sensors. Image sensor companies have showed sensor demonstrations to replace Si-CIS (CMOS Image Sensor), which accounts for most of the global image sensor market, with organic CIS.[1-3] In particular, unlike inorganic materials, organic material have absorption characteristic of selective wavelength, therefore stacked image sensor can be fabricated with especially green selective organic material. The stacked image sensor with green colour absorbed organic semiconductor material have the advantage of increasing sensing area and increasing sensitivity. In addition, it has the advantage of increasing the number of effective pixels compared to the same pixel size, becoming increased the resolution of the image sensor.[4]<br/>Sensors applied with organic materials are expanding not only to image sensors for cameras but also to bio-recognition sensors in display of mobile. Currently, MUT (Micromechanic Ultrasonic Transducer) and optical Si CIS are used as the authorized finger-print sensors in the form of chips underneath the OLED display. If organic light sensors are applied as bio-recognition sensors, certain sensing areas about the size of existing chips (1cm~2cm) can be expanded to all areas of the display. As a result, multi-fingerprint and palm recognition can be possible, which can enhance security functions.[5,6]<br/>Although it is an early development stage in the field of beyond 6G optical wireless communication, Organic photodetectors, such as organic photodiodes (OPD)and organic photovoltaics (OPV), can be manufactured with a large detection area and a high optical gain. Additionally, these can be operated without an external bias voltage, extending their application range. The optional external bias voltage results in increased efficiency and response time. he present work introduces a high-bandwidth OPD device with a bandwidth of 1.4 MHz, which is nearly a factor of ten faster than the fastest previously reported. Additionally, much faster data rates are demonstrated through the convergence of a preequalization and machine learning (ML)-based digital signal processing technique (DSP). The data transfer rates achieved are 30 Mbps (zero bias) and 150 Mbps (−4 V bias).[7]<br/>In order to contribute the expectations of these diverse electronic devices, organic absorbent molecules would become an important material for information and communication electronic devices in the future due to their high absorption wavelength selectivity and specific characteristic of circular dichroism compared to conventional inorganic materials.<br/> <br/><b>References</b><br/>Martin K., et al.: Ultrathin and lightweight organic solar cells with high flexibility, <i>Nature Comm</i>., 3, 770 (2012).<br/>Kazuko N., et al.: Advanced features of layered-structure organic-photoconductive-film CMOS image sensor: Over 120dB wide dynamic range function and photoelectric-conversion-controlled global shutter function, <i>Jap. J. of Appl. Phys</i>., 57, 1002B4 (2018).<br/>Togashi H., et al.: Three-layer Stacked Color Image Sensor With 2.0-μm Pixel Size Using Organic Photoconductive Film, <i>IEDM</i>, 16.6.2, 386 (2019).<br/>Moon Gyu H., et al.: Narrow-Band Organic Photodiodes for High-Resolution Imaging, <i>ACS Appl. Mater. Interfaces</i>, 8, 26143 (2016).<br/>Hylke A., et al.: Measuring Health Parameters with Large-Area Organic Photodetector Arrays, SID Symposium Digest, 6-1, 43 (2021).<br/>Kamada, T. et al. OLED Display Incorporating Organic Photodiodes for Fingerprint Imaging. <i>Journal of the Society for Information Display</i> <b>27</b>, 361–371 (2019)<br/>Seonghyeon C., et al.: Small Molecule Based Organic Photo Signal Receiver for High-Speed Optical Wireless Communications, <i>Adv. Sci.</i>, 2203715 (2022)