Perovskite solar cells are remarkably efficient; however, they are prone to degradation in water, oxygen and ultraviolet light. Cation engineering in 3D perovskite absorbers has led to reduced degradation. Alternatively, 2D Ruddlesden–Popper layered perovskites exhibit improved stability, but have not delivered efficient solar cells so far. Here, we introduce n-butylammonium cations into a mixed-cation lead mixed-halide FA_0.83Cs_0.17Pb(I_yBr_1−y)₃ 3D perovskite. We observe the formation of 2D perovskite platelets, interspersed between highly orientated 3D perovskite grains, which suppress non-radiative charge recombination. We investigate the relationship between thin-film composition, crystal alignment and device performance. Solar cells with an optimal butylammonium content exhibit average stabilized power conversion efficiency of 17.5 ± 1.3% with a 1.61-eV-bandgap perovskite and 15.8 ± 0.8% with a 1.72-eV-bandgap perovskite. The stability under simulated sunlight is also enhanced. Cells sustain 80% of their ‘post burn-in’ efficiency after 1,000 h in air, and close to 4,000 h when encapsulated.

钙钛矿太阳能电池非常有效；但是，它们易于在水，氧气和紫外线下降解。3D钙钛矿吸收器中的阳离子工程技术降低了降解。另外，二维Ruddlesden-Popper钙钛矿层表现出更高的稳定性，但到目前为止尚未提供高效的太阳能电池。在这里，我们将正丁基铵阳离子引入混合阳离子铅-混合卤化物FA _0.83 Cs _0.17 Pb（I _y Br _{1- y}）_3中3D钙钛矿。我们观察到2D钙钛矿薄片的形成，散布在高度取向的3D钙钛矿颗粒之间，可抑制非辐射电荷复合。我们研究了薄膜组成，晶体取向和器件性能之间的关系。具有最佳丁基铵含量的太阳能电池具有1.61 eV带隙钙钛矿的平均稳定功率转换效率为17.5±1.3％，具有1.72 eV带隙钙钛矿的平均稳定功率转换效率为15.8±0.8％。在模拟阳光下的稳定性也得到增强。电池在空气中放置1000小时后，其“后老化”效率达到80％，而封装后则接近4000小时。