Synergy of ammonium chloride and moisture on perovskite crystallization for efficient printable mesoscopic solar cells

Organometal lead halide perovskites have been widely used as the light harvester for high-performance solar cells. However, typical perovskites of methylammonium lead halides (CH(3)NH(3)PbX(3), X=Cl, Br, I) are usually sensitive to moisture in ambient air, and thus require an inert atmosphere to process. Here we demonstrate a moisture-induced transformation of perovskite crystals in a triple-layer scaffold of TiO(2)/ZrO(2)/Carbon to fabricate printable mesoscopic solar cells. An additive of ammonium chloride (NH(4)Cl) is employed to assist the crystallization of perovskite, wherein the formation and transition of intermediate CH(3)NH(3)X·NH(4)PbX(3)(H(2)O)(2) (X=I or Cl) enables high-quality perovskite CH(3)NH(3)PbI(3) crystals with preferential growth orientation. Correspondingly, the intrinsic perovskite devices based on CH(3)NH(3)PbI(3) achieve an efficiency of 15.6% and a lifetime of over 130 days in ambient condition with 30% relative humidity. This ambient-processed printable perovskite solar cell provides a promising prospect for mass production, and will promote the development of perovskite-based photovoltaics.