Two-dimensional (2D) and quasi-2D modifications of three-dimensional (3D) perovskite active layers have contributed to advances in the performance of perovskite solar cells (PSCs). However, the ionic diffusion between the surface 2D and bulk 3D perovskites leads to the degradation of the 3D/2D perovskite heterostructures and limits the long-term stability of PSCs. Here we incorporate a cross-linked polymer (CLP) on the top of a 3D perovskite layer and then deposit a 2D perovskite layer via a vapour-assisted two-step process to form a 3D/CLP/2D perovskite heterostructure. Photoluminescence spectra and thickness-profiled elemental analysis indicate that the CLP stabilizes the heterostructure by inhibiting the diffusion of cations (formamidinium, FA⁺ and 4-fluorophenylethylammonium, 4F-PEA⁺) between the 2D and 3D perovskites. For devices based on carbon electrodes, we report small-area devices with an efficiency of 21.2% and mini-modules with an efficiency of 19.6%. Devices retain 90% of initial performance after 4,390 hours operation under maximum power point tracking and one-sun illumination at elevated temperatures.

三维 (3D) 钙钛矿活性层的二维 (2D) 和准二维改性有助于钙钛矿太阳能电池 (PSC) 性能的提高。然而，表面 2D 和块状 3D 钙钛矿之间的离子扩散导致 3D/2D 钙钛矿异质结构的降解，并限制了 PSC 的长期稳定性。在这里，我们在 3D 钙钛矿层的顶部加入交联聚合物 (CLP)，然后通过蒸汽辅助两步工艺沉积 2D 钙钛矿层，形成 3D/CLP/2D 钙钛矿异质结构。光致发光光谱和厚度剖面元素分析表明，CLP 通过抑制阳离子（甲脒、FA ⁺和 4-氟苯基乙基铵、4F-PEA ^{+）的扩散来稳定异质结构}）介于 2D 和 3D 钙钛矿之间。对于基于碳电极的设备，我们报告了效率为 21.2% 的小面积设备和效率为 19.6% 的微型模块。在高温下最大功率点跟踪和单日光照条件下运行 4,390 小时后，设备仍可保持 90% 的初始性能。