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

• Published in: Advanced optical materials 2023-03, Vol.11 (5), p.n/a
• Main Authors: Kim, Min Soo, Luo, Dou, Jang, Woongsik, Kim, Byung Gi, Shan, Chengwei, Kyaw, Aung Ko Ko, Wang, Dong Hwan
• Format: Article
• Language: English
• Subjects: 1‐chloronaphthalene; Charge transfer; Dark current; Materials science; nonfused ring electron acceptors; Optics; organic photodetectors; phase separation; Photoelectric effect; Photoelectricity; Photometers; Photosensitivity; Sensors; Thickness; TPDC‐4F
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202202525

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. Nonfused ring electron acceptor‐based organic photodetectors (OPDs) are developed by controlling the morphology and thickness of the photosensitive layer by introduction of 1‐chloronaphthalene (1‐CN) additive. The optimized OPDs show higher optical detection properties than pristine devices based on not only the dramatically suppressed dark current but also the favorable charge transfer properties via 1‐CN‐induced vertical phase distribution.