Noncapacitive Hysteresis in Perovskite Solar Cells at Room Temperature

The current density-voltage (J-V) curves of perovskite solar cells have been found to present a hysteresis-like distortion when the measurement is done by sweeping the applied voltage at different scan conditions. Hysteresis has raised many concerns about the feasibility and long-term stability of this kind of photovoltaic technology. However, there is a lack of distinction among different hysteretic phenomena which is necessary to unravel its underlying physical and chemical mechanisms. Here we distinguish between capacitive and noncapacitive currents giving rise to specific hysteretic responses in the J-V curves of PSCs. It is reported that capacitive current causing hysteresis dominates in regular structures with TiO2 as bottom electron selective layer. This is mainly caused by the charge, both ionic and electronic, accumulation ability of the TiO2/perovskite interface but has no influence on the steady-state operation. Noncapacitive hysteresis is observable at slow enough scan rates in all kind of architectures. Inverted structures, including organic compounds as bottom hole selective layers and fullerene materials as top contact, exhibit larger noncapacitive distortions because of the inherent reactivity of contact materials and absorber perovskites.