Effect of Cation and anion migration toward contacts on Perovskite solar cell performance

Despite the rapid and promising progress on the perovskite solar cell efficiency of around ۲۵.۷ % in the last few years, the ion migration as an intrinsic instability has limited the practical application of these solar cells. In this work, we have modified the common drift-diffusion equations to model the experimental current-voltage (J-V) hysteresis in Perovskite solar cells. In our model, both anions and cations have been considered. Inverted hysteresis behavior in J-V characteristics and contact corrosion in perovskite solar cells have yet to be explained clearly. To address this issue, we modified ionic-electronic transport equations by adding ionic flux equations to let ions move from the perovskite layer toward contacts. Our results show a strong inverted hysteresis because of the high flux rate of anions and cations to ETL and HTL and, consequently, toward contacts. Although the ionic flux may cause the instability of the perovskite solar cells, the efficiency is increased for the cases where anions and cations flux to HTL and ETL toward contacts. In all ionic flux models, open circuit voltages (Voc) are increased due to ionic accumulation at interfaces, the built-higher gradient of electric potentials at interfaces, and the modified Fermi level (modified work function-aging process).

Keywords:

hysteresis , ion migration , ionic flux , contact corrosion