Constructing three-dimensional (3D)/two-dimensional (2D) hybrid perovskite heterojunction has been proved to be a promising approach to improve the power conversion efficiency (PCE) and environmental stability of perovskite solar cells (PSCs). Here, an organic ammonium salt, cyclohexylmethylammonium bromide (CMABr), is deposited atop the primary 3D perovskite film to form ultrathin 2D perovskite with residual PbI₂ between the light-absorbing layer and the hole transport layer (HTL). The in-situ wide-band-gap 2D perovskite layer could play a multifunctional role in passivating the surface defects and protecting the underlying 3D perovskite film from humidity, resulting in the significantly suppressed non-radiative recombination process and superior moisture stability. As a result, a maximum PCE of 21.80% was obtained for the 3D/2D PSC as compared to that (19.62%) of pure 3D device. Moreover, the unencapsulated devices with 2D perovskite capping layer exhibited excellent long-term durability and mitigated hysteresis in contrast with the control device. Our study confirms that building 3D/2D perovskite heterojunctions by the utilization of organic ammonium salts is an effective way to develop highly efficient and stable PSCs.

构建三维 (3D)/二维 (2D) 混合钙钛矿异质结已被证明是提高钙钛矿太阳能电池 (PSC) 的功率转换效率 (PCE) 和环境稳定性的一种有前景的方法。在这里，有机铵盐、环己基甲基溴化铵 (CMABr) 沉积在初级 3D 钙钛矿膜的顶部，以形成超薄 2D 钙钛矿，在光吸收层和空穴传输层 (HTL) 之间具有残留的 PbI ₂。在原位宽带隙 2D 钙钛矿层可以在钝化表面缺陷和保护底层 3D 钙钛矿薄膜免受潮湿方面发挥多功能作用，从而显着抑制非辐射复合过程和优异的水分稳定性。结果，与纯 3D 设备的 PCE (19.62%) 相比，3D/2D PSC 获得了 21.80% 的最大 PCE。此外，与控制器件相比，具有 2D 钙钛矿覆盖层的未封装器件表现出优异的长期耐用性和减轻的滞后现象。我们的研究证实，利用有机铵盐构建 3D/2D 钙钛矿异质结是开发高效稳定 PSC 的有效方法。