美国纽约大学Andr D. Taylor团队报道了钙钛矿型太阳能电池有机夹层的CO2掺杂策略。相关研究成果于2021年6月2日发表在国际知名学术期刊《自然》。
在钙钛矿型太阳能电池中，掺杂的有机半导体常被用作位于光活性层和电极之间的电荷提取层。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（螺氧基甲醚）是最常用的空穴半导体导电层，其电学性质对太阳能电池的电荷收集效率有很大影响。为了提高螺甲醚的导电性，双（三氟甲烷）磺酰亚胺锂（LiTFSI）通常用于掺杂过程，通常通过将螺甲醚：LiTFSI共混膜暴露于空气和光中数小时来启动掺杂过程。在氧作为p型掺杂剂时，掺杂过程是时间密集型的，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。
该文中，研究人员报告了一种快速和可重复的掺杂方法，即在紫外光下用二氧化碳鼓泡螺甲胺：LiTFSI溶液。二氧化碳从光激发的螺甲醚中获得电子，迅速促进其p型掺杂并导致碳酸盐的沉淀。经CO2处理的中间层显示出比原始薄膜高约100倍的电导率，同时实现了无需任何后处理的稳定、高效的钙钛矿型太阳能电池。研究表明，该方法可以用于涂料π-共轭聚合物。
附：英文原文
Title: CO2 doping of organic interlayers for perovskite solar cells
Author: Jaemin Kong, Yongwoo Shin, Jason A. Rhr, Hang Wang, Juan Meng, Yueshen Wu, Adlai Katzenberg, Geunjin Kim, Dong Young Kim, Tai-De Li, Edward Chau, Francisco Antonio, Tana Siboonruang, Sooncheol Kwon, Kwanghee Lee, Jin Ryoun Kim, Miguel A. Modestino, Hailiang Wang, Andr D. Taylor
Issue&Volume: 2021-06-02
Abstract: 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 layer1,2,3,4,5,6, 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 dopant8,9,10,11, 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.
DOI: 10.1038/s41586-021-03518-y
Source: https://www.nature.com/articles/s41586-021-03518-y