Space-charge-limited electron and hole currents in hybrid organic-inorganic perovskites.

Hybrid organic-inorganic perovskites are promising materials for the application in solar cells and light-emitting diodes. However, the basic current-voltage behavior for electrons and holes is still poorly understood in these semiconductors due to their mixed electronic-ionic character. Here, we present the analysis of space-charge-limited electron and hole currents in the archetypical perovskite methyl ammonium lead iodide (MAPbI). We demonstrate that the frequency dependence of the permittivity plays a crucial role in the analysis of space-charge-limited currents and their dependence on voltage scan rate and temperature. Using a mixed electronic-ionic device model based on experimentally determined parameters, the current-voltage characteristics of single-carrier devices are accurately reproduced. Our results reveal that in our solution processed MAPbI thin films transport of electrons dominates over holes. Furthermore, we show that the direction of the hysteresis in the current-voltage characteristics provides a fingerprint for the sign of the dominant moving ionic species.