The stability and photovoltaic performance enhancement of inorganic CsPbI2Br perovskite through in situ growth of 2D CsPb2I4Br perovskite capping layer
The amelioration of perovskite quality and the enhancement of perovskite stability are key factors for further promoting the photovoltaic performance of inorganic perovskite solar cells.Herein,we develop a novel surface reconstruction strategy for in situ growing 2D CsPb2I4Br capping layer on the surface of inorganic CsPbI2Br perovskite to form the 2D CsPb2I4Br/3D CsPbI2Br bilayer perovskite heterojunction.The surface reconstruction reaction triggers the secondary crystallization of CsPbI2Br perovskite,decreasing the perovskite defects and promoting the perovskite quality.The formation of a 2D CsPb2I4Br capping layer effectively protects CsPbI2Br perovskite against the external damage,considerably enhancing the stability of CsPbI2Br perovskite.Moreover,the construction of 2D CsPb2I4Br/3D CsPbI2Br bilayer perovskite heterojunction enhances the charge separation and transport,greatly decreasing the charge recombination.As a result,the assembled carbon-based CsPbI2Br perovskite solar cell without the hole-transport layer delivers a high conversion efficiency of 14.29％,which is increased by 29％compared with the efficiency of the pristine device.Furthermore,the unencapsulated cell remains over 90％of its initial efficiency after 900 h of storage under ambient conditions,demonstrating an excellent stability.
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