Lai Qian, Zhuang Rongshan, Zhang Kun, Wu Tai, Xie Lin, Zhao Rongjun, Yang Lei, Wang Yang, Hua Yong
School of Materials and Energy, Yunnan University, 650091, Kunming, China.
Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, P. R. China.
Angew Chem Int Ed Engl. 2023 Aug 1;62(31):e202305670. doi: 10.1002/anie.202305670. Epub 2023 Jun 26.
Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) has been identified as the most used and effective p-dopant for hole transport layer (HTL) in perovskite solar cells (PSCs). However, the migration and agglomeration of Li-TFSI in HTL negatively impact PSCs performance and stability. Herein, we report an effective strategy for adding a liquid crystal organic small molecule (LQ) into Li-TFSI doped (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'- spirobifluorene (Spiro-OMeTAD) HTL. It was found that the introduction of LQ into Spiro-OMeTAD HTL can efficiently enhance the charge carrier extraction and transportation in device, which can strongly retard the charge carrier recombination in device. Consequently, the PSCs efficiency is significantly enhanced to 24.42 % (Spiro-OMeTAD+LQ) from 21.03 % (Spiro-OMeTAD). The chemical coordination between LQ and Li-TFSI can strongly confine Li ions migration and agglomeration of Li-TFSI, thus, achieving the enhanced device stability. Only a 9 % efficiency degradation is observed for un-encapsulated device prepared with Spiro-OMeTAD and LQ after 1700 h under air environment, while the efficiency drops by 30 % for the reference device. This work provides an effective strategy for improving the efficiency and stability of PSCs, and gives some important insights for understanding intrinsic hot carriers dynamics for perovskite-based optoelectronic devices.
双（三氟甲磺酰）亚胺锂（Li-TFSI）已被确定为钙钛矿太阳能电池（PSC）中空穴传输层（HTL）最常用且有效的p型掺杂剂。然而，Li-TFSI在HTL中的迁移和团聚对PSC的性能和稳定性产生负面影响。在此，我们报道了一种有效的策略，即在Li-TFSI掺杂的（2,2',7,7'-四（N,N-二对甲氧基苯胺）-9,9'-螺二芴（Spiro-OMeTAD）HTL中添加液晶有机小分子（LQ）。研究发现，将LQ引入Spiro-OMeTAD HTL能够有效增强器件中的电荷载流子提取和传输，从而强烈抑制器件中的电荷载流子复合。因此，PSC的效率从21.03%（Spiro-OMeTAD）显著提高到24.42%（Spiro-OMeTAD+LQ）。LQ与Li-TFSI之间的化学配位能够强烈限制锂离子的迁移和Li-TFSI的团聚，从而实现器件稳定性的增强。在空气环境下，用Spiro-OMeTAD和LQ制备的未封装器件在1700小时后仅观察到9%的效率降解，而参考器件的效率下降了30%。这项工作为提高PSC的效率和稳定性提供了一种有效策略，并为理解基于钙钛矿的光电器件的本征热载流子动力学提供了一些重要见解。
