Dynamic halide perovskite heterojunction generates direct current

Abstract

Here, we demonstrate a dynamic perovskite device capable of converting mechanical energy into direct current (DC) electrical energy, combining two concepts: carrier generation from the triboelectric effect and carrier separation through band energy level difference. By analyzing and comparing different perovskite (FAPbI₃, MAPbI₃, MAPbBr₃, PEA₂PbI₄, etc.) and charge transport layer (CTL) materials (spiro-MeOTAD, PTAA, TiO₂, SnO₂, etc.), the key rules for determining DC output and performances are identified: (1) a suitable band alignment (band position and bandgap) between perovskite and CTL can separate the carrier transfer; (2) a large difference in work function between two layers leads to high electrical potential difference; and (3) a high carrier concentration can enhance the DC power-generating performances. Furthermore, it is found that the light illumination acts as a stimulus to current output to a large extent, which is due to the coupling effect from triboelectric and photovoltaic effects. This study provides a set of key rules to explain the mechanism and to further improve the performance of the dynamic perovskite/CTL heterojunction.