Large Photomultiplication by Charge-Self-Trapping for High-Response Quantum Dot Infrared Photodetectors
Kaimin Xu, Liang Ke, Hongbin Dou, Rui Xu, Wenjia Zhou, Qi Wei, Xinzuo Sun, Hao Wang, Haobo Wu, Lin Li, Jiamin Xue, Baile Chen, Tsu‐Chien Weng, Li Zheng, Yuehui Yu, Zhijun Ning
Abstract
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.