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In recent years, there has been a surge in research efforts to utilize organic−inorganic lead halide perovskites (OLHPs) in optoelectronic devices (e.g., concentrator photovoltaics) requiring high light illumination. Yet, knowledge of the physics of photocarriers in perovskites in the high-excitation regime is limited. Here, we investigate carrier and exciton dynamics that are manifested under strong light illumination in methyl ammonium lead bromide perovskite nanocrystals (NCs) using ultrafast pump-probe spectroscopy. We demonstrate that the carrier trapping process is highly excitation intensity dependent because of a potential barrier that isolates trap states from the band edge. At low excitation densities, holes are unable to cross the energy barrier, but holes undergo trapping at moderate densities (1018–1020 cm–3). The charge carrier trapping is negligible due to the dominance of higher-order Auger processes at high excitation density (>1020 cm–3). We suggest that the effect of trap states is likely to be insignificant for perovskite concentrator solar cells.

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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 ultrathin TiO2 films. The designed CH3NH3PbBr3 QD/TiO2 bilayer device displays inclusive performance with on/off ratio of 6.3 × 102, responsivity of 85 A W−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 photodetector through interface engineering. We believe that this work can provide a strategy to accelerate development of high-performance solution-processed perovskite photodetectors.