Photoluminescence-voltage (PL-V) hysteresis of perovskite solar cells

This article investigates the effect of an external electric field on the photoluminescence (PL) of a methylammonium lead iodide (MAPbI₃) film in a working solar cell architecture. Our study reveals hysteretic PL intensity responses when changing the voltage scanning direction, namely, PL-V hysteresis. The external electric field is found to have multiple effects on the photoexcited states of PSCs. First, an external electric field instantaneously changes the drift velocity of photogenerated charge carriers. Second, it drives ion migration and thus generates an induced electric field which screens the external field. Third, the ion migration driven by the external electric field also changes the distribution and density of charge traps that are responsible for nonradiative recombination. The first effect leads to instant PL change which is not responsible for PL-V hysteresis, while the other two effects are closely related to the slow kinetics of ion migration and lead to the PL-V hysteresis in perovskite solar cells.