 A mismatch between quasi-femi-level splitting and open circuit voltage is detrimental to wide bandgap perovskite pin solar cells. Here, through theoretical and experimental approaches, the authors optimize N and P-type interfaces to achieve open circuit voltage of 1.29 V and T80 of 3585 degrees Celsius. This article was authored by Pietro Capriolio, Joel A. Smith, Robert D. J. Oliver, and others.