Ionic Charge Imbalance in Perovskite Solar Cells

TL;DR

This paper investigates how ionic charge imbalance, caused by external ion migration or chemical reactions, affects the electrostatics, stability, and performance of perovskite solar cells, challenging the traditional charge neutrality assumption.

Contribution

It reveals the effects of ionic imbalance on device electrostatics, stability, and hysteresis, providing new insights into perovskite solar cell behavior beyond charge neutrality models.

Findings

Ionic imbalance causes electrostatic asymmetry in devices.

Imbalance impacts stability and degradation.

Material/interface design influences device performance.

Abstract

Ion migration in perovskite solar cells is usually analyzed and understood in terms of charge neutrality condition. However, several recent reports indicate possibility of ionic imbalance in the active layer due to external ion migration and/or chemical reactions. In this context, here we explore the influence of ionic charge neutrality on the performance of perovskite solar cells. Our results indicate that ionic imbalance leads to an asymmetry in the device electrostatics, which have interesting implications on the impact of material/interface degradation, hysteresis, and finally on the long-term stability and influence of optimal device architecture (NIP vs. PIN).