Suppressed Non-Radiative Recombination in Formamidinium Lead Triiodide under Electric Activation

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The high carrier lifetime of metal halide perovskite (MHP) materials is closely related to the microscopic crystallographic structure. However, the detailed correlation between the lattice structure and carrier dynamics remains unclear. In this work, we found a correlation between lattice strain and open-circuit voltage (Voc) of MHP under electric activation. It is observed that the non-radiative recombination of MHP solar cells is progressively suppressed under elevated residual strain under an electric field. Moreover, the electric activation reduced the density of ions, which permanently switched off the ionic movement in the strained lattice structure. Resultantly, the Voc of cubic formamidinium lead triiodide under electric activation elevated to 1.21 V, which is only 59 mV lower than the theoretical limit of the material. This Voc represents one of the highest values for the same band gap of MHP. This resulted in a high power conversion efficiency (PCE) of 24.15%.