Theory of light-induced degradation in perovskite solar cells

Abstract

One of the fundamental challenges that have prevented practical use of the perovskite solar cell is the current degradation in exposure conditions, causing instability of the power conversion efficiency. We present here a theory for this current degradation in perovskite solar cells. Many researchers attribute this degradation to the vacancies migration in the perovskite layer. But there are two fundamental ambiguities in the theories presented for the ion migration process. First, according to the assumptions of these theories, this vacancy migration to the sides of the perovskite layer should also happen in dark conditions, while this occurs only in exposure conditions. Second, according to the assumptions of these theories, the degraded solar cell should not be recovered in dark conditions, while recovery takes place in dark conditions. The approach we present in this paper provides a good understanding of the processes of degradation and recovery in perovskite solar cells, as well as resolves these ambiguities.