Organic-inorganic halide perovskites (OIHPs) is one of the strong candidates for the next generation photodetector material, because they have attractive properties such as tunable band gap, high light absorption, high carrier mobility, and compatibility with flexible substrates.
In this study, we report the improved performance of OIHP photodiode (OIHP PD) by engineering electron transport layer (ETL). We adopted ZnO nanoparticles (NPs) as an electron transport layer (ETL) material.
Because the grain itself or the grain boundaries of ZnO NPs serve as conduction channel or depletion region respectively, it can be easily inferred that the ETL with relatively large ZnO NPs would show better charge transportation properties due to the reduction of grain boundaries. However, the both enhancement of dark current and bright current is not always advantageous in achieving high performance PDs, because the detectivity (D*) of PD is directly associated with the current on-off ratio. So, we tried to optimize the performance of OIHP photodiodes by adopting ZnO ETL NPs with inhomogeneous size distribution. This approach successfully enhanced the external quantum efficiency and detectivity of photodiodes.