Bimolecularly passivated interface enables efficient and stable inverted perovskite solar cells
Cheng Liu, Yi Yang, Hao Chen, Jian Xu, Ao Liu, Abdulaziz S. R. Bati, Huihui Zhu, Luke Grater, Shreyash Hadke, Chuying Huang, Vinod K. Sangwan, Tong Cai, Donghoon Shin, Lin X. Chen, Mark C. Hersam, Chad A. Mirkin, Bin Chen, Mercouri G. Kanatzidis, Edward H. Sargent
Abstract
Compared with the n-i-p structure, inverted (p-i-n) perovskite solar cells (PSCs) promise increased operating stability, but these photovoltaic cells often exhibit lower power conversion efficiencies (PCEs) because of nonradiative recombination losses, particularly at the perovskite/C 60 interface. We passivated surface defects and enabled reflection of minority carriers from the interface into the bulk using two types of functional molecules. We used sulfur-modified methylthio molecules to passivate surface defects and suppress recombination through strong coordination and hydrogen bonding, along with diammonium molecules to repel minority carriers and reduce contact-induced interface recombination achieved through field-effect passivation. This approach led to a fivefold longer carrier lifetime and one-third the photoluminescence quantum yield loss and enabled a certified quasi-steady-state PCE of 25.1% for inverted PSCs with stable operation at 65°C for >2000 hours in ambient air. We also fabricated monolithic all-perovskite tandem solar cells with 28.1% PCE.