Perovskite solar cells show excellent power conversion efficiencies, long carrier diffusion lengths and low recombination rates. This encourages a view that intragrain defects are electronically benign with little impact on device performance. In this study we varied the methylammonium (MA)/formamidinium (FA) composition in MA_1–xFA_xPbI₃ (x = 0–1), and compared the structure and density of the intragrain planar defects with device performance, otherwise keeping the device nominally the same. We found that charge carrier lifetime, open-circuit voltage deficit and current density–voltage hysteresis correlate empirically with the density and structure of {111}_c planar defects (x = 0.5–1) and {112}_t twin boundaries (x = 0–0.1). The best performance parameters were found when essentially no intragrain planar defects were evident (x = 0.2). Similarly, reducing the density of {111}_c planar defects through MASCN vapour treatment of FAPbI₃ (x ≈ 1) also improved performance. These observations suggest that intragrain defect control can provide an important route for improving perovskite solar cell performance, in addition to well-established parameters such as grain boundaries and interfaces.

钙钛矿太阳能电池显示出优异的功率转换效率、长载流子扩散长度和低复合率。这鼓励了一种观点，即晶粒内缺陷在电子方面是良性的，对设备性能的影响很小。_{在这项研究中，我们改变了 MA 1 - x} FA _x PbI ₃ ( x = 0-1)中的甲基铵 (MA)/甲脒 (FA) 组成 ，并将晶内平面缺陷的结构和密度与器件性能进行了比较，否则保持该设备名义上相同。我们发现电荷载流子寿命、开路电压不足和电流密度 - 电压滞后在经验上与 {111} _c平面缺陷的密度和结构相关（x  = 0.5–1) 和 {112} _t孪晶边界 ( x  = 0–0.1)。当基本上没有明显的晶粒内平面缺陷 ( x  = 0.2) 时，发现了最佳性能参数。_{类似地，通过 FAPbI 3} ( x ≈ 1)的 MASCN 蒸汽处理降低 {111} _c平面缺陷的密度 也提高了性能。这些观察结果表明，除了晶界和界面等完善的参数外，晶内缺陷控制可以为提高钙钛矿太阳能电池性能提供重要途径。