High-Sensitivity Organic Photodetector Based on Surface-Concentrated Nonfused Ring Electron Acceptor

초록

Organic photodetectors (OPDs) with high photodetection abilities are essential requirements for ubiquitous light-sensing devices. This work presents a simple nonfused ring electron acceptor (NFREA) named “TPDC-4F” having optical bandgap of 1.42 eV, being designed as an efficient OPD via thickness control and additive engineering of the photosensitive layer. The optimized photosensitive layer composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PM6) donors and TPDC-4F acceptors shows a dramatically suppressed dark current of 3.55 × 10−9 A cm−2. Moreover, it shows improved photoelectric properties and fast charge transfer even though the photosensitive layer thickness is as large as 330 nm. OPDs based on the 330-nm-thick PM6:TPDC-4F with 1-chloronaphthalene additive exhibit a high specific detectivity (D*) of 1.27 × 1013 cm Hz1/2 W−1 at 800 nm and a linear dynamic range of 122 dB under a bias of −0.1 V. The device also exhibits fast rise and fall times of 6.81 and 5.41 µs, respectively. This work demonstrates that the NFREA-based OPDs offer competitive device performance compared to those based on fused-ring electron acceptors. © 2022 Wiley-VCH GmbH.

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