In perovskite solar cells, doped organic semiconductors are often used as charge-extraction interlayers situated between the photoactive layer and the electrodes. The π-conjugated small molecule 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD) is the most frequently used semiconductor in the hole-conducting layer^1,2,3,4,5,6, and its electrical properties considerably affect the charge collection efficiencies of the solar cell⁷. To enhance the electrical conductivity of spiro-OMeTAD, lithium bis(trifluoromethane)sulfonimide (LiTFSI) is typically used in a doping process, which is conventionally initiated by exposing spiro-OMeTAD:LiTFSI blend films to air and light for several hours. This process, in which oxygen acts as the p-type dopant^8,9,10,11, is time-intensive and largely depends on ambient conditions, and thus hinders the commercialization of perovskite solar cells. Here we report a fast and reproducible doping method that involves bubbling a spiro-OMeTAD:LiTFSI solution with CO₂ under ultraviolet light. CO₂ obtains electrons from photoexcited spiro-OMeTAD, rapidly promoting its p-type doping and resulting in the precipitation of carbonates. The CO₂-treated interlayer exhibits approximately 100 times higher conductivity than a pristine film while realizing stable, high-efficiency perovskite solar cells without any post-treatments. We also show that this method can be used to dope π-conjugated polymers.

在钙钛矿太阳能电池中，掺杂的有机半导体通常用作位于光敏层和电极之间的电荷提取中间层。π共轭小分子2,2′,7,7′-四[ N , N-二(4-甲氧基苯基)氨基]-9,9-螺二芴(spiro-OMeTAD)是空穴中最常用的半导体-导电层^1,2,3,4,5,6，其电学特性显着影响太阳能电池^{7的电荷收集效率}. 为了提高螺-OMeTAD 的电导率，双（三氟甲烷）磺酰亚胺锂 (LiTFSI) 通常用于掺杂过程，该过程通常通过将螺-OMeTAD:LiTFSI 混合膜暴露在空气和光线下几个小时来引发。这个过程，其中氧气作为 p 型掺杂剂^8,9,10,11是时间密集型的并且很大程度上取决于环境条件，因此阻碍了钙钛矿太阳能电池的商业化。在这里，我们报告了一种快速且可重复的掺杂方法，该方法包括在紫外光下用 CO ₂使 spiro-OMeTAD:LiTFSI 溶液起泡。CO ₂从光激发的螺-OMeTAD 中获得电子，迅速促进其p 型掺杂并导致碳酸盐的沉淀。CO ₂经过处理的中间层表现出比原始薄膜高约 100 倍的电导率，同时无需任何后处理即可实现稳定、高效的钙​​钛矿太阳能电池。我们还表明，该方法可用于掺杂 π 共轭聚合物。