Nature Energy
- Perovskite
Diamine chelates for increased stability in mixed Sn–Pb and all-perovskite tandem solar cells
Authors Chongwen Li, Lei Chen, Fangyuan Jiang, Zhaoning Song, Xiaoming Wang, Adam Balvanz, Esma Ugur, Yuan Liu, Cheng Liu, Aidan Maxwell, Hao Chen, Yanjiang Liu, Zaiwei Wang, Pan Xia, You Li, Sheng Fu, Nannan Sun, Corey R. Grice, Xuefei Wu, Zachary Fink, Qin Hu, Lewei Zeng, Euidae Jung, Junke Wang, So Min Park, Deying Luo, Cailing Chen, Jie Shen, Yu Han, Carlo Andrea Riccardo Perini, Juan-Pablo Correa-Baena, Zheng-Hong Lu, Thomas P. Russell, Stefaan De Wolf, Mercouri G. Kanatzidis, David S. Ginger, Bin Chen, Yanfa Yan & Edward H. Sargent
Abstract
Perovskite tandem solar cells show promising performance, but non-radiative recombination and its progressive worsening with time, especially in the mixed Sn–Pb low-bandgap layer, limit performance and stability. Here we find that mixed Sn–Pb perovskite thin films exhibit a compositional gradient, with an excess of Sn on the surface—and we show this gradient exacerbates oxidation and increases the recombination rate. We find that diamines preferentially chelate Sn atoms, removing them from the film surface and achieving a more balanced Sn:Pb stoichiometry, making the surface of the film resistive to the oxidation of Sn. The process forms an electrically resistive low-dimensional barrier layer, passivating defects and reducing interface recombination. Further improving the homogeneity of the barrier layer using 1,2-diaminopropane results in more uniform distribution and passivation. Tandems achieve a power conversion efficiency of 28.8%. Encapsulated tandems retain 90% of initial efficiency following 1,000 h of operating at the maximum power point under simulated one-sun illumination in air without cooling.