Ultrasensitivity broadband photodetectors based on perovskite: Research on film crystallization and electrode optimization

Abstract

Broad absorption bandwidth photodetectors based on organo-metal halide perovskite absorbers is an attractive means of resolving the narrow absorption of organic semiconductors. Here we report the achievement and characterization of broad spectral photodetectors based on CH3NH3PbI3−xClx, which has been optimized with four different electrodes and a specially modified highly crystallized active layer. This work use six different lasers which wavelength range from ∼405 nm to ∼808 nm as the illuminations, and shows clearly that the Au electrode devices have ultrahigh photosensitivity (P=IphIdark=Iill−IdarkIdark, up to 3.5 × 106 at incident light power of 38 mW/cm2) and such low dark current of ∼0.01 nA at −10 V. In addition, we achieved a relatively high photoresponsivity of 11.5 A/W at incident optical power ∼0.8 μW/cm2 for Ag electrode devices. Furthermore, this work demonstrates that the devices of Al electrode have an unexpected low performance, which has been proved to be caused by serious oxidization through XPS test results, this unpopularity may due to the roughness morphology at the interface and instability of Al chemical property. Our work will provide a strategy to fabricate facile and ultrasensitive broadband photodetectors with perovskite as absorber and several familiar metals as electrodes.