Defect Passivation and Energy Level Modulation of CsPbBr2I QDs for High‐Detectivity and Stable Photodetectors

Abstract High‐detectivity and stable photodetectors (PDs) have been intensively concerned in the field of wireless optical communication, among which perovskite material has become a prospective candidate owing to its outstanding photoelectric properties. However, the defects and mismatched energy levels of perovskite material can significantly reduce the detectivity and stability of PDs. Herein, the CsPbBr2I quantum dots (CQDs) with the surface modulation via potassium trifluoroacetate (KTFA) are utilized to deserve high‐detectivity and stable PDs. The surface modulation for CQDs not only passivates defects by inhibiting vacancies, but also enhances hole transport capacity by modulating energy level mismatch. As a result, the assembled CsPbBr2I PDs show a responsivity of 0.375 A W−1, a detectivity of 1.12 × 1013 Jones and an on/off ratio of 104. More importantly, the CsPbBr2I PDs exhibit excellent long‐term stability for 12 weeks and can withstand 1000 bending cycles. This work provides a guideline for the development of perovskite in wireless optical communication.