Wide-bandgap perovskites (WBPs) are attractive candidates for constructing tandem photovoltaic devices, but they are often much more prone to defect formation and other interfacial problems. Fixing these problems can boost the performance of WBP solar cells and is thus crucial for achieving a high overall energy conversion efficiency. Toward this end, we performed a systematic study on the construction of a 2D/3D heterostructure on the WBP surface to passivate the defects and to regulate the interfacial properties by varying the chain length of alkylammonium bromides in the 2D part. Hexanelammonium bromide (HABr) was found to be the champion in multiple respects. The optimized interfacial energy band structure and the reduced defect density with HABr allowed to achieve a remarkable 19.8% photovoltaic efficiency with a prominent open-circuit voltage (V_OC) of 1.31 V. HABr also reduced interfacial capacitance by improving hole transport, substantially alleviating the hysteresis of the corresponding devices. Last but not least, the HABr-induced hydrophobicity in the 2D layer can not only block moisture, but also retard migration of the alkali cations from the perovskites across the interface, eventually endowing the WBP based devices with a superior moisture stability.

宽带隙钙钛矿 (WBP) 是构建串联光伏器件的有吸引力的候选材料，但它们通常更容易形成缺陷和其他界面问题。解决这些问题可以提高 WBP 太阳能电池的性能，因此对于实现高整体能量转换效率至关重要。为此，我们对在 WBP 表面上构建 2D/3D 异质结构进行了系统研究，以钝化缺陷并通过改变 2D 部分中烷基溴化铵的链长来调节界面特性。发现己酮溴化铵 (HABr) 在多个方面都是冠军。优化的界面能带结构和 HABr 降低的缺陷密度允许达到显着的 19。V _OC ) 为 1.31 V。HABr 还通过改善空穴传输降低了界面电容，大大减轻了相应器件的滞后。最后但并非最不重要的是，2D 层中 HABr 诱导的疏水性不仅可以阻挡水分，还可以阻止碱金属阳离子从钙钛矿穿过界面迁移，最终使基于 WBP 的器件具有优异的水分稳定性。