Pre‐Buried Additive for Cross‐Layer Modification in Flexible Perovskite Solar Cells with Efficiency Exceeding 22%

Abstract Halide perovskites have shown superior potentials in flexible photovoltaics due to their soft and high power‐to‐weight nature. However, interfacial residual stress and lattice mismatch due to the large deformation of flexible substrates have greatly limited the performance of flexible perovskite solar cells (F‐PSCs). Here, ammonium formate (HCOONH 4 ) is used as a pre‐buried additive in electron transport layer (ETL) to realize a bottom‐up infiltration process for an in situ, integral modification of ETL, perovskite layer, and their interface. The HCOONH 4 treatment leads to an enhanced electron extraction in ETL, relaxed residual strain and micro‐strain in perovskite film, along with reduced defect…

• NN
  National Natural Science Foundation of China

  Award: 62004027
• DO
  Department of Science and Technology of Sichuan Province

  Awards: 2019JDTD0006, 2021ZYD0048
• NK
  National Key Research and Development Program of China

  Award: 2017YFA0207400