  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).
