• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.143-150
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• 2023

Underwater wireless communication is a challenging issue for realizing the smart aqua-farm and various marine activities for exploring the ocean and environmental monitoring. In comparison to acoustic and radio frequency technologies, the visible light communication is the most promising method to transmit data with a higher speed in complex underwater environments. To send data at a speedier rate, high-performance photodetectors are essentially required to receive blue and/or cyan-blue light that are transmitted from the light sources in a light-fidelity (Li-Fi) system. Here, we fabricated high-performance organic phototransistors (OPTs) based on P-type donor polymer (PTO2) and N-type acceptor small molecule (IT-4F) blend semiconductors. Bulk-heterojunction (BHJ) PTO2:IT-4F photo-active layer has a broad absorption spectrum in the range of 450~550 nm wavelength. Solution-processed OPTs showed a high photo-responsivity >1,000 mA/W, a large photo-sensitivity >10³, a fast response time, and reproducible light-On/Off switching characteristics even under a weak incident light. BHJ organic semiconductors absorbed photons and generated excitons, and efficiently dissociated to electron and hole carriers at the donor-acceptor interface. Printed and flexible OPTs can be widely used as Li-Fi receivers and image sensors for underwater communication and underwater internet of things (UIoTs).

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.79-80
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• 2007

A high performance organic phototransistor with dynamic range of 120 dB is demonstrated by employing soluble pentacene as a photo-sensing layer. The organic phototransistor used suspended source/drain (SSD) electrode structure, which provides a dark current level of ${\sim}10^{-14}$ A at positive gate bias. Under a steady-state illumination, the organic phototransistor exhibited a current modulation of $10^6$ compared to dark to give a dynamic range of 120 dB. These results suggest that the organic phototransistor based on TIPS pentacene can be a new premising candidate for low-cost and high-performance photo-sensing element for digital imaging applications.