Zheng Xueqing, Jiang Tingming, Bai Lizhong, Chen Xu, Chen Zeng, Xu Xuehui, Song Dongdong, Xu Xiaojian, Li Bo, Yang Yang Michael
Department of Applied Physics, College of Science, Zhejiang University of Technology Hangzhou 310023 People's Republic of China
State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University Hangzhou Zhejiang People's Republic of China
RSC Adv. 2020 May 13;10(31):18400-18406. doi: 10.1039/d0ra03238g. eCollection 2020 May 10.
Inverted perovskite solar cells (PSCs) have recently gained increasing attention because of the long operation lifetime achieved. However, bathocuproine (BCP): a commonly used buffer layer in inverted PSCs, is experimentally confirmed by us to show fast aggregation at the temperature of 85 °C, which is the protocol temperature required by the International Electrotechnical Commission (IEC) standard. This thermal instability of the BCP interfacial layer makes long-term thermal stability of inverted PSCs questionable. Simply removing or replacing it can directly lead to an inferior PCE of a device. We solve this problem by removing the BCP layer and simultaneously increasing the thickness of C, which obtains a high efficiency of 18% comparable with the device with BCP. This is possibly attributed to the extended migration path of carriers from C to metal electrode Ag, consequently reducing the carrier accumulation at the interface. In addition to the interfacial modification, the addition of ionic liquid: BMIMBF into perovskite can further improve a device's thermal stability by its effective suppression of perovskite decomposition. The devices with 0.4 mol% of BMIMBF exhibit promising thermal stability by retaining 80% of their initial PCE after thermal aging of 400 h at 85 °C.
倒置钙钛矿太阳能电池（PSCs）因其实现的长运行寿命最近受到越来越多的关注。然而，我们通过实验证实，倒置PSCs中常用的缓冲层浴铜灵（BCP）在85°C时会快速聚集，而这是国际电工委员会（IEC）标准要求的测试温度。BCP界面层的这种热不稳定性使得倒置PSCs的长期热稳定性受到质疑。简单地去除或替换它会直接导致器件的功率转换效率（PCE）降低。我们通过去除BCP层并同时增加C层的厚度来解决这个问题，这样得到了与带有BCP的器件相当的18%的高效率。这可能归因于载流子从C层到金属电极Ag的迁移路径延长，从而减少了界面处的载流子积累。除了界面修饰外，向钙钛矿中添加离子液体BMIMBF可以通过有效抑制钙钛矿分解进一步提高器件的热稳定性。含有0.4 mol% BMIMBF的器件在85°C下热老化400小时后保留了其初始PCE的80%，表现出良好的热稳定性。
