Journal Article perovskite photovoltaics defect passivation active‐matrix displays blue LEDs borax crystallization detoxification strategy downward crystallization flexible photovoltaics grain boundary in vivo experiments indoor photovoltaics interfacial charge loss ion-dipole interaction lead capture lead isolation mechanical stability perovskites phase distribution phase rearrangement quasi‐2D perovskites quasi‐2D template red quasi‐2D perovskites thermodynamics control vapor‐assisted crystallization