A High‐Performance Solution‐Processed Organic Photodetector for Near‐Infrared Sensing

• Published in: Advanced materials (Weinheim) Vol. 32; no. 1; pp. e1906027 - n/a
• Main Authors: Huang, Jianfei, Lee, Jaewon, Vollbrecht, Joachim, Brus, Viktor V., Dixon, Alana L., Cao, David Xi, Zhu, Ziyue, Du, Zhifang, Wang, Hengbin, Cho, Kilwon, Bazan, Guillermo C., Nguyen, Thuc‐Quyen
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.01.2020
• Subjects: bulk heterojunctions; Dark current; high responsivity; Infrared radiation; Leakage current; Materials science; near‐infrared; organic photodiodes; photodetectors; Photodiodes; Photometers; Space charge; photodetectors; high responsivity; bulk heterojunctions; near-infrared; organic photodiodes
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201906027

Sensitive detection of near‐infrared (NIR) light enables many important applications in both research and industry. Current organic photodetectors suffer from low NIR sensitivity typically due to early absorption cutoff, low responsivity, and/or large dark/noise current under bias. Herein, organic photodetectors based on a novel ultranarrow‐bandgap nonfullerene acceptor, CO1‐4Cl, are presented, showcasing a remarkable responsivity over 0.5 A W−1 in the NIR spectral region (920–960 nm), which is the highest among organic photodiodes. By effectively delaying the onset of the space charge limited current and suppressing the shunt leakage current, the optimized devices show a large specific detectivity around 1012 Jones for NIR spectral region up to 1010 nm, close to that of a commercial Si photodiode. The presented photodetectors can also be integrated in photoplethysmography for real‐time heart‐rate monitoring, suggesting its potential for practical applications. Highly efficient near‐infrared (NIR) detection is realized with solution‐processed bulk‐heterojunction organic photodetectors based on a novel ultranarrow‐bandgap nonfullerene acceptor. The photodetectors show extraordinary responsivity in the NIR region of 920–940 nm, good linearity, and fast response. The photodetectors also compete favorably in detectivity with a commercial silicon photodiode and are applicable to photoplethysmography.