Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183 Linköping, Sweden.
Korea Institute of Energy Research (KIER), Ulsan, Republic of Korea.
Science. 2022 Jul 29;377(6605):495-501. doi: 10.1126/science.abo2757. Epub 2022 Jul 28.
Record power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been obtained with the organic hole transporter 2,2',7,7'-tetrakis(,-di--methoxyphenyl-amine)9,9'-spirobifluorene (spiro-OMeTAD). Conventional doping of spiro-OMeTAD with hygroscopic lithium salts and volatile 4--butylpyridine is a time-consuming process and also leads to poor device stability. We developed a new doping strategy for spiro-OMeTAD that avoids post-oxidation by using stable organic radicals as the dopant and ionic salts as the doping modulator (referred to as ion-modulated radical doping). We achieved PCEs of >25% and much-improved device stability under harsh conditions. The radicals provide hole polarons that instantly increase the conductivity and work function (WF), and ionic salts further modulate the WF by affecting the energetics of the hole polarons. This organic semiconductor doping strategy, which decouples conductivity and WF tunability, could inspire further optimization in other optoelectronic devices.
钙钛矿太阳能电池的记录功率转换效率（PCE）已经通过有机空穴传输体 2,2',7,7'-四（N，N-二对甲氧基苯基胺）-9,9'-螺二芴（spiro-OMeTAD）获得。传统的 spiro-OMeTAD 掺杂具有吸湿性的锂盐和挥发性 4--丁基吡啶是一个耗时的过程，也会导致器件稳定性差。我们开发了一种新的 spiro-OMeTAD 掺杂策略，通过使用稳定的有机自由基作为掺杂剂和离子盐作为掺杂调节剂（称为离子调制自由基掺杂）来避免后氧化。我们在恶劣条件下实现了超过 25%的 PCE 和显著提高的器件稳定性。自由基提供空穴极化子，瞬间增加电导率和功函数（WF），而离子盐通过影响空穴极化子的能态进一步调节 WF。这种有机半导体掺杂策略，解耦了电导率和 WF 的可调性，可能会激发其他光电设备的进一步优化。
