High-Performance and Stable Colloidal Quantum Dots Imager via Energy Band Engineering
Linxiang Zhang, Long Chen, Junrui Yang, Jing Liu, Shuaicheng Lu, Xinyi Liang, Xuezhi Zhao, Yang Yang, Jun Hu, Long Hu, Xinzheng Lan, Jianbing Zhang, Liang Gao, Jiang Tang
Abstract
Solution-processed colloidal quantum dot (CQD) photodiodes are compatible for monolithic integration with silicon-based readout circuitry, enabling ultrahigh resolution and ultralow cost infrared imagers. However, top-illuminated CQD photodiodes for longer infrared imaging suffer from mismatched energy band alignment between narrow-bandgap CQDs and the electron transport layer. In this work, we designed a new top-illuminated structure by replacing the sputtered ZnO layer with a SnO 2 layer by atomic layer deposition. Benefiting from matched energy band alignment and improved heterogeneous interface, our top-illuminated CQD photodiodes achieve a broad-band response up to 1650 nm. At 220 K, these SnO 2 -based devices exhibit an ultralow dark current density of 3.5 nA cm –2 at −10 mV, reaching the noise limit for passive night vision. The detectivity is 4.1 × 10 12 Jones at 1530 nm. These SnO 2 -based devices also demonstrate exceptional operation stability. By integrating with silicon-based readout circuitry, our CQD imager realizes water/oil discrimination and see-through smoke imaging.