Photovoltage/photocurrent transient techniques

Methods based on photovoltage and photocurrent transients are powerful characterization tools for perovskite solar cells. Such methods are easy to apply on solar cell devices and allow for characterization under conditions that are very close to operational conditions. The methods can be divided into small modulation methods, where a small perturbation is applied on top of a base light intensity, and large modulation methods, where the light is switched on or off. In both types of method the device voltage or current is recorded in time during/after the excitation and analyzed. Important information on carrier transport, accumulation and recombination kinetics can be extracted. In contrast to conventional solar cells, perovskite solar cells also exhibit ionic motion, which can give rise to hysteresis effects. Furthermore, light can induce defects in the lead halide perovskite. These properties make the observed transient response more complex. Careful analysis can give useful insights into the transport and recombination kinetics of charge carriers and the accumulation and transport or ionic charge in perovskite photovoltaic devices.