Temperature- and Bias-Dependent Degradation and Regeneration of Perovskite Solar Cells with Organic and Inorganic Hole Transport Layers

Hybrid halide perovskite solar cells have drawn widespread attention with the achievement of high power conversion efficiencies. However, poor stability remains the greatest barrier preventing their commercialization. Performance degradation and recovery have a complicated dependence on the environment and a dependence on the applied bias, which affects ion migration. Herein, solar cells with an organic hole transport layer and cells with an inorganic hole transport layer are compared. A type of degradation of the organic transport layer is examined, which is reversible by applying a forward bias soak, and how the degradation arises from ion migration mechanisms is explained. Experimental current-voltage and capacitance transient measurements are conducted as a function of temperature. The resulting S-kink and positive capacitance decay are explained in terms of the modeled effects of a changing ion density at the hole transport layer. An irreversible degradation is found upon heating to more than 100 degrees C. On the contrary, the inorganic hole transport layer is found to eliminate the observable effects of ion migration, even at elevated temperatures, so long as air exposure is avoided.