LAUSR

As a power conversion efficiency (PCE) of perovskite solar cells (PSCs) has rapidly increased up to 25.7% in 2022, a curiosity about the achievable limit of PCE has prevailed and demands understanding about the underlying fundamentals to step forward. Meanwhile, outstanding long-term stability of PSCs over 1000 h has been reported at operating condition or under damp heat test with 85 °C/85% RH. Here comes a question whether the phase stability issue of perovskite crystal is completely resolved in the most recent state-of-the-art perovskite film or deceives us into believing by significantly slowing the kinetics. On one hand, we thoroughly examine the fundamental origins of a discrepancy between a reported value and its theoretical limit, where the importance of light management is greatly emphasized with introducing external luminescence as a key parameter to narrow the gap. On the other hand, the phase stability of perovskite film is understood from thermodynamic point of view to address viable approaches to lower Gibbs free energy with distinguishing the kinetically trapped condition from the thermodynamically stable phase. This article is protected by copyright. All rights reserved.