Perovskite solar cells are becoming increasingly popular. However, exactly how the design of perovskite solar cells affects their performance is still unclear. Perovskite composition is certainly key but, surprisingly, materials with very different cations and halide ratios have similar performance results.

Emilio Palomares, Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology (BIST), Tarragona, Spain, and Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain, and colleagues have studied the relationship between the perovskite structure, ion migration processes, and charge transfer processes using photo-induced charge extraction (PICE) measurements. During these experiments, the team fully charged solar cells and then short-circuited them. The voltage decay during this process is measured to investigate the details of charge migration processes.

The researchers found that different kinetics in PICE are due to ion migration and recombination processes. Moreover, the experiments demonstrated that perovskite devices can store charges beyond the light-generated ones, in contrast to dye-sensitized solar cell (DSSC) and organic photovoltaics (OPV) alternatives. These extra charges seem to be a direct consequence of ion migration processes.

• Photo-Induced Dynamic Processes in Perovskite Solar Cells. The Influence of Perovskite Composition in the Charge Extraction and the Carriers Recombination,
  Emilio J. Palomares, Nuria Fernandez-Montcada, Maria Mendez, Kyung Taek Cho, Mohammad Khaja Nazeeruddin,
  Nanoscale 2018.
  https://doi.org/10.1039/c8nr00180d