Affiliation:
1. Xiamen Key Laboratory of Optoelectronic Materials and Advanced Manufacturing Institute of Luminescent Materials and Information Displays College of Materials Science and Engineering Huaqiao University Xiamen 361021 China
2. CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China
Abstract
AbstractImproving the efficiency of tin‐based perovskite solar cells (TPSCs) is significantly hindered by energy level mismatch and weak interactions at the interface between the tin‐based perovskite and fullerene‐based electron transport layers (ETLs). In this study, four well‐defined multidentate fullerene molecules with 3, 4, 5, and 6 diethylmalonate groups, labeled as FM3, FM4, FM5, and FM6 are synthesized, and employed as interfacial layers in TPSCs. It is observed that increasing the number of functional groups in these fullerenes leads to shallower lowest unoccupied molecular orbital (LUMO) energy levels and enhance interfacial chemical interactions. Notably, FM5 exhibits a suitable energy level and robust interaction with the perovskite, effectively enhancing electron extraction and defect passivation. Additionally, the unique molecular structure of FM5 allows the exposed carbon cage to be tightly stacked with the upper fullerene cage after interaction with the perovskite, facilitating efficient charge transfer and protecting the perovskite from moisture and oxygen damage. As a result, the FM5‐based device achieves a champion efficiency of 15.05%, significantly surpassing that of the PCBM‐based (11.77%), FM3‐based (13.54%), FM4‐based (14.34%), and FM6‐based (13.75%) devices. Moreover, the FM5‐based unencapsulated device exhibits excellent stability, maintaining over 90% of its initial efficiency even after 300 h of air exposure.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Fujian Province