Large Photomultiplication by Charge-Self-Trapping for High-Response Quantum Dot Infrared Photodetectors

• Published in: ACS applied materials & interfaces 2022-03, Vol.14 (12), p.14783-14790
• Main Authors: Xu, Kaimin, Ke, Liang, Dou, Hongbin, Xu, Rui, Zhou, Wenjia, Wei, Qi, Sun, Xinzuo, Wang, Hao, Wu, Haobo, Li, Lin, Xue, Jiamin, Chen, Baile, Weng, Tsu-Chien, Zheng, Li, Yu, Yuehui, Ning, Zhijun
• Format: Article
• Language: English
• Subjects: Surfaces, Interfaces, and Applications
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c01046

PbS colloidal quantum dots (CQDs) are emerging as promising candidates for next-generation, low-cost, and high-performance infrared photodetectors. Recently, photomultiplication has been explored to improve the detectivity of CQD infrared photodetectors by doping charge-trapping material into a matrix. However, this relies on remote doping that could influence carrier transfer giving rise to limited photomultiplication. Herein, a charge-self-trapped ZnO layer is prepared by a surface reaction between acid and ZnO. Photogenerated electrons trapped by oxygen vacancy defects at the ZnO surface generate a strong interfacial electrical field and induce large photomultiplication at extremely low bias. A PbS CQD infrared photodiode based on this structure shows a response (R) of 77.0 A·W–1 and specific detectivity of 1.5 × 1011 Jones at 1550 nm under a −0.3 V bias. This self-trapped ZnO layer can be applied to other photodetectors such as perovskite-based devices.