Enhancement of device performances in a Cs2AgBiBr6 perovskite photodetector by dual-site defect passivation with a zwitterion additive

Abstract

Passivation of defects such as surface-related defects and grain boundaries is an essential step to enhance the device performance and stability of metal halide perovskite (MHP)-based photodetectors (PDs). Here, we introduce a zwitterion additive, 3-(1-pyridinio)-1-propane sulfonate (PPS), into a Cs2AgBiBr6-based visible PD to simultaneously passivate both cationic and anionic defects in Cs2AgBiBr6. Using PPS, the dark current of a pristine PD decreased significantly, from 8.88 x 10-12 A to 7.27 x 10- 13 A. In addition, the PPS-added Cs2AgBiBr6 PD exhibited responsivity and detectivity of 0.99 A W- 1 and 5.51 x 1013 Jones under 405 nm illumination with an intensity of 4.13 nW cm- 2, values that were 19.8 times and 37.5 times greater than those of pristine PD, respectively. The PD showed excellent stability for 60 h under comparatively high (more than 65 %) relative humidity. Our study provides a new approach to defect passivation and highlights the potential of zwitterion additives in improving the performance and stability of lead-free, perovskite-based optoelectronic devices.