Ion induced passivation of grain boundaries in perovskite solar cells

Abstract

Demonstration of high efficiency large area cells with excellent stability is an important requirement towards the commercialization of perovskite solar cells (PSCs). With reports of high quality perovskite grains, it is evident that the performance of such large area cells will be strongly influenced by phenomena like carrier recombination and ion migration at grain boundaries (GBs). Here, we develop a modeling framework to address performance limitations due to GBs in large area PSCs. Through detailed numerical simulations, we show that photo-carrier recombination has a nontrivial dependence on the orientation of GBs. We find that ions at GBs lead to significant performance improvement through field effect passivation, which is influenced by critical parameters like density and polarity of ions, and the location of GBs. These results could have interesting implications toward long term stability and hence are relevant for the performance optimization of large area polycrystalline based thin film solar cells.