  Organo-lead halide perovskite materials have opened up a great opportunity to
develop high performance photodetectors because of their superior
optoelectronic properties. The main issue with perovskite-only photodetector is
severe carrier recombination. Integration of perovskite with high-conductive
materials such as graphene or transition metal sulfides certainly improved the
photoresponsivity. However, achieving high overall performance remains a
challenge. Here, an improved photodetector is constructed by perovskite quantum
dots (QDs) and atomic layer deposited (ALD) ultrathin TiO2 films. The designed
CH3NH3PbBr3 QD/TiO2 bilayer device displays inclusive performance with on/off
ratio of 6.3x102, responsivity of 85 AW-1, and rise/decay time of 0.09/0.11 s.
Furthermore, we demonstrate that interface plays a crucial role in determining
the device current and enhance the overall performance of heterostructure
photodetectors through interface engineering. We believe that this work can
provide a strategy to accelerate development of high-performance
solution-processed perovskite photodetectors.
