原位生长2D CsPb_(2)I_(4)Br表面层增强无机CsPbI_(2)Br钙钛矿稳定性及光电性能

The stability and photovoltaic performance enhancement of inorganic CsPbI_(2)Br perovskite through in situ growth of 2D CsPb_(2)I_(4)Br perovskite capping layer

提高无机钙钛矿材料的质量和结构稳定性是进一步提高无机钙钛矿太阳能电池光电性能的关键.本文通过表面重构反应在无机CsPbI_(2)Br钙钛矿表面原位生成2D CsPb_(2)I_(4)Br层,形成2D CsPb_(2)I_(4)Br/3D CsPbI_(2)Br双层无机钙钛矿异质结结构.CsPbI_(2)Br钙钛矿表面重构反应引发钙钛矿二次结晶,明显减少了CsPbI_(2)Br钙钛矿缺陷,提高了钙钛矿质量.2D CsPb_(2)I_(4)Br表面层的形成能有效保护CsPbI_(2)Br钙钛矿不受外界侵蚀,显著增强了钙钛矿的稳定性.2D CsPb_(2)I_(4)Br/3D CsPbI_(2)Br双层无机钙钛矿异质结增强了电荷分离和传输,减少了电荷复合.采用2D CsPb_(2)I_(4)Br/3D CsPbI_(2)Br双层无机钙钛矿材料组装的碳基太阳能电池效率达到14.29%,与初始CsPbI_(2)Br钙钛矿电池效率相比提高了29%,而且,CsPbI_(2)Br钙钛矿太阳能电池的稳定性也有了显著提高.空气环境中贮存900 h,未密封电池效率仍能保持初始值的90%以上.

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 CsPb_(2)I_(4)Br capping layer on the surface of inorganic CsPbI_(2)Br perovskite to form the 2D CsPb_(2)I_(4)Br/3D CsPbI_(2)Br bilayer perovskite heterojunction.The surface reconstruction reaction triggers the secondary crystallization of CsPbI_(2)Br perovskite,decreasing the perovskite defects and promoting the perovskite quality.The formation of a 2D CsPb_(2)I_(4)Br capping layer effectively protects CsPbI_(2)Br perovskite against the external damage,considerably enhancing the stability of CsPbI_(2)Br perovskite.Moreover,the construction of 2D CsPb_(2)I_(4)Br/3D CsPbI_(2)Br bilayer perovskite heterojunction enhances the charge separation and transport,greatly decreasing the charge recombination.As a result,the assembled carbon-based CsPbI_(2)Br 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.