Revealing the Variation of Photodetectivity in MAPbI3and MAPb(I0.88Br0.12)3Single Crystal Based Photodetectors under Electrical Poling-Induced Polarization

Abstract

The use of electrical poling to induce polarization potential has been found to increase the photocurrent (Ilight) in hybrid perovskite-based devices; however, the origin of this process has not been fully understood. Here, we study the effect of electrical poling on the photodetection properties of self-powered photodetectors (PDs) based on halide perovskites in two different phase structures (i.e., tetragonal and cubic). Specifically, extensive investigations are performed on the MAPbI3 (tetragonal) and MAPb(I0.88Br0.12)3 (cubic) single crystals (SCs). Our characterization results revealed that the Ilight has increased by 2-fold during forward poling and decreased during reverse poling in both PDs. The improved Ilight is caused by polarization induced ion migration, which builds remanent potential due to ion accumulation near metal electrodes. The effect of this polarization was found to be greater in MAPbI3 PD as compared to MAPb(I0.88Br0.12)3 PD, which influences the interface band bending and reduces Schottky barrier height (SBH). This study highlights that the modification of SBH, which describes the potential energy barrier for electrons formed at a metal-semiconductor junction, can tune the photocurrent and response time of PDs.