Dopants, which are often indispensable in the organic hole-transport layer (HTL) in perovskite solar cells (PSCs), are used to enhance HTL conductivity and tune the energy level of HTLs. Here, we show that the lithium (Li) dopant from HTLs can significantly dope the perovskite absorber layer through diffusion. Kelvin probe force microscopy mapping shows that Li diffusion increases the surface potential of the perovskite film. The potential at grain boundaries showed more increase than in grain interiors, indicating inhomogeneous distribution of Li dopant in the perovskite layer, which was further confirmed by lateral elemental mapping using time-of-flight secondary ion mass spectrometry. For both p-i-n and n-i-p device structures, the diffusion and nonuniform distribution of Li⁺ ions are shown to influence the carrier-transport properties of perovskites and device characteristics. This work reveals the hidden doping effects of the HTL dopants on perovskite films and their impact on PSC performance.

钙钛矿型太阳能电池（PSC）中有机空穴传输层（HTL）中通常不可缺少的掺杂剂，用于增强HTL的电导率和调整HTL的能级。在这里，我们显示了来自HTL的锂（Li）掺杂剂可以通过扩散显着地掺杂钙钛矿吸收剂层。开尔文探针力显微镜测图表明，锂的扩散增加了钙钛矿膜的表面电势。晶界处的电势显示出比晶粒内部更多的电势，这表明锂掺杂物在钙钛矿层中的分布不均匀，这通过使用飞行时间二次离子质谱法进行的横向元素标测进一步得到了证实。对于销和压区设备结构，Li的扩散和不均匀分布已显示⁺离子会影响钙钛矿的载流子传输特性和器件特性。这项工作揭示了HTL掺杂剂对钙钛矿薄膜的隐藏掺杂效应及其对PSC性能的影响。