Identifying Dominant Recombination Mechanisms in Perovskite Solar Cells by Measuring the Transient Ideality Factor

The ideality factor of a solar cell, derived from the dependence of its open-circuit voltage VOC on light intensity, has historically been used to identify the dominant mechanism of charge-carrier recombination in a device. Applying this technique to perovskite solar cells (PSCs) is problematic, though, since VOC values change with time, due to the presence of slowly mobile ionic charge in the perovskite layer. Using both transient optoelectronic measurements and drift-diffusion simulations, the authors identify the dominant recombination mechanism in PSCs from the t00exr00exa00exn00exs00exi00exe00exn00ext ideality factor, following device preconditioning with a forward bias.