Bifunctional hole-shuttle molecule for improved interfacial energy level alignment and defect passivation in perovskite solar cells
Shuai You, Felix T. Eickemeyer, Jing Gao, Jun‐Ho Yum, Xin Zheng, Dan Ren, Meng Xia, Rui Guo, Yaoguang Rong, Shaik M. Zakeeruddin, Kevin Sivula, Jiang Tang, Zhongjin Shen, Xiong Li, Michaël Grätzel
Abstract
Abstract Perovskite solar cells have reached a power conversion efficiency over 25%, and the engineering of the interface between the perovskite and hole transport layer (HTL) has been crucial to achieve high performance. Here we design a bifunctional molecule CBz-PAI with carbazole-triphenylamine and phenylammonium iodide units to passivate defects at the perovskite/HTL interface. Owing to a favourable energy level alignment with the perovskite, the CBz-PAI acts as a hole shuttle between the perovskite layer and the HTL. This minimizes the difference between the quasi-Fermi level splitting of the perovskite, or ‘internal’ V oc , and the external device V oc , thus reducing voltage losses. As a result, solar cells incorporating CBz-PAI reach a stabilized power conversion efficiency of 24.7% and maintain 92.3% of the initial efficiency after 1,000 h under damp heat test (85 °C and 85% relative humidity) and 94.6% after 1,100 h under maximum power point-tracking conditions.