Zhang Ying, Zhou Chenxiao, Lin Lizhi, Pei Fengtao, Xiao Mengqi, Yang Xiaoyan, Yuan Guizhou, Zhu Cheng, Chen Yu, Chen Qi
Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Experimental Center of Advanced Materials, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
Nanomicro Lett. 2023 Jul 10;15(1):175. doi: 10.1007/s40820-023-01145-y.
To achieve high power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs), a hole transport layer (HTL) with persistently high conductivity, good moisture/oxygen barrier ability, and adequate passivation capability is important. To achieve enough conductivity and effective hole extraction, spiro-OMeTAD, one of the most frequently used HTL in optoelectronic devices, often needs chemical doping with a lithium compound (LiTFSI). However, the lithium salt dopant induces crystallization and has a negative impact on the performance and lifetime of the device due to its hygroscopic nature. Here, we provide an easy method for creating a gel by mixing a natural small molecule additive (thioctic acid, TA) with spiro-OMeTAD. We discover that gelation effectively improves the compactness of resultant HTL and prevents moisture and oxygen infiltration. Moreover, the gelation of HTL improves not only the conductivity of spiro-OMeTAD, but also the operational robustness of the devices in the atmospheric environment. In addition, TA passivates the perovskite defects and facilitates the charge transfer from the perovskite layer to HTL. As a consequence, the optimized PSCs based on the gelated HTL exhibit an improved PCE (22.52%) with excellent device stability.
为实现钙钛矿太阳能电池（PSC）的高功率转换效率（PCE）和长期稳定性，具有持续高导电性、良好防潮/氧能力以及足够钝化能力的空穴传输层（HTL）至关重要。为实现足够的导电性和有效的空穴提取，螺环-OMeTAD作为光电器件中最常用的HTL之一，通常需要用锂化合物（LiTFSI）进行化学掺杂。然而，锂盐掺杂剂会诱导结晶，并且由于其吸湿性，会对器件的性能和寿命产生负面影响。在此，我们提供了一种通过将天然小分子添加剂（硫辛酸，TA）与螺环-OMeTAD混合来制备凝胶的简便方法。我们发现凝胶化有效地提高了所得HTL的致密性，并防止了水分和氧气的渗透。此外，HTL的凝胶化不仅提高了螺环-OMeTAD的导电性，还提高了器件在大气环境中的运行稳健性。此外，TA钝化了钙钛矿缺陷，并促进了电荷从钙钛矿层转移到HTL。因此，基于凝胶化HTL的优化PSC表现出更高的PCE（22.52%）以及出色的器件稳定性。
