Surface passivation by congeneric quantum dots for high-performance and stable CsPbBr3-based photodetectors

CsPbBr3-based photodetectors (PDs) have aroused enormous attention owing to their low-cost solution processing, outstanding optoelectronic properties, and remarkable stability. However, their performance remains a big challenge to meet the requirements for practical applications due to severe carrier recombination caused by the inferior film quality. Herein, we demonstrated that the introduction of congeneric CsPbBr3 quantum dots (QDs) to decorate the surface of CsPbBr3 films can effectively improve the surface morphology and reduce the surface defects. After detailed characterizations, we can infer that the functions of the QDs are to fill the pinholes, cracks, and grain boundaries and passivate the uncoordinated Pb and Br ions. Subsequently, PDs with a device architecture of indium tin oxide (ITO)/ZnO/CsPbBr3 film/CsPbBr3 QDs/Au electrode are fabricated, exhibiting a high responsivity of 0.88 A W−1, a superior specific detectivity of 2.15 × 1012 Jones, a large linear dynamic range of 119 dB, and a fast rise (fall) time of 8.1 μs (27.2 μs) at zero bias. The value of the maximum detectivity can reach 7.53 × 1012 Jones when operated at a bias of 0.04 V. Besides, a negligible change of performance is observed after 1000 hours of storage under 60% relative humidity conditions, which verifies the excellent stability of our PDs. Superior performance and stability suggest that our surface passivation method with congeneric QDs is feasible and can pave the way for future commercial applications of perovskite PDs.