Session:

Perovskite tandem solar cells promise performance beyond the detailed balance limit of single-junction solar cells; however, non-radiative recombination and its progressive worsening with time, especially in the mixed Sn–Pb low-bandgap layer, currently limit performance and stability. 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 the rate of recombination. We develop a materials processing strategy wherein diamines preferentially chelate Sn atoms, removing them from the film surface and achieving a more balanced Sn:Pb stoichiometry, making film surface resistive to Sn oxidation. This process forms electrically-resistive low-dimensional barrier layers, passivating defects and reducing interface recombination. Further regulating the dimensionality of the barrier layer to 0-D 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 1000 hours operating at the maximum power point under simulated one-sun illumination in air without cooling.

Co-Author(s): Lei Chen (The University of Toledo), Fangyuan Jiang (University of Washington), Zhaoning Song (The University of Toledo), Bin Chen (Northwestern University), Xiaoming Wang (The University of Toledo), Esma Ugur (King Abdullah University of Science and Technology), Adam Balvan (Northwestern University), Xuefei Wu (Lawrence Berkeley National Laboratory), Zachary Fink (Lawrence Berkeley National Laboratory), Carlo Andrea Riccardo Perini (Georgia Institute of Technology), Juan-Pablo Correa-Baena (Georgia Institute of Technology), Zheng-Hong Lu (University of Toronto), Thomas Russell (Lawrence Berkeley National Laboratory), Stefaan De Wolf (King Abdullah University of Science and Technology), Mercouri Kanatzidis (Northwestern University), David Ginger (University of Washington), Yanfa Yan (The University of Toledo), Edward Sargent (Northwestern University)

Chongwen Li

Appearances