Regulating surface potential maximizes voltage in all-perovskite tandems

• Published in: Nature (London) 2023-01, Vol.613 (7945), p.676-681
• Main Authors: Chen, Hao, Maxwell, Aidan, Li, Chongwen, Teale, Sam, Chen, Bin, Zhu, Tong, Ugur, Esma, Harrison, George, Grater, Luke, Wang, Junke, Wang, Zaiwei, Zeng, Lewei, Park, So Min, Chen, Lei, Serles, Peter, Awni, Rasha Abbas, Subedi, Biwas, Zheng, Xiaopeng, Xiao, Chuanxiao, Podraza, Nikolas J., Filleter, Tobin, Liu, Cheng, Yang, Yi, Luther, Joseph M., De Wolf, Stefaan, Kanatzidis, Mercouri G., Yan, Yanfa, Sargent, Edward H.
• Format: Article
• Language: English
• Subjects: 119/118; 140/125; 140/146; 639/301/299/946; 639/301/357/995; 639/4077/909/4101/4096/946; 639/766/1130/2799; Electron transport; Energy conversion efficiency; Humanities and Social Sciences; Ligands; Microscopy; multidisciplinary; Open circuit voltage; Perovskites; Photovoltaic cells; Quasi-steady states; Recombination; Science; Science (multidisciplinary); Solar cells; Spatial distribution; Splitting; Surface treatment; Voltage
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-05541-z

The open-circuit voltage ( V OC ) deficit in perovskite solar cells is greater in wide-bandgap (over 1.7 eV) cells than in perovskites of roughly 1.5 eV (refs.  1 , 2 ). Quasi-Fermi-level-splitting measurements show V OC -limiting recombination at the electron-transport-layer contact 3 – 5 . This, we find, stems from inhomogeneous surface potential and poor perovskite–electron transport layer energetic alignment. Common monoammonium surface treatments fail to address this; as an alternative, we introduce diammonium molecules to modify perovskite surface states and achieve a more uniform spatial distribution of surface potential. Using 1,3-propane diammonium, quasi-Fermi-level splitting increases by 90 meV, enabling 1.79 eV perovskite solar cells with a certified 1.33 V V OC and over 19% power conversion efficiency (PCE). Incorporating this layer into a monolithic all-perovskite tandem, we report a record V OC of 2.19 V (89% of the detailed balance V OC limit) and over 27% PCE (26.3% certified quasi-steady state). These tandems retained more than 86% of their initial PCE after 500 h of operation. Because open-circuit voltage deficit is greater in wide-bandgap perovskite solar cells, the authors introduce diammonium molecules to modify perovskite surface states and achieve a more uniform spatial distribution of surface potential, enabling record voltage all-perovskite tandem solar cells.