2, School of Advanced Materials Engineering, Kookmin University, Seoul, , Korea (the Republic of)
In spite of the unprecedented advance of MAPbI3-based perovskite solar cell, there are still remaining issues to be resolved for its industrial applications. Especially, hysteresis in current-voltage (I-V) curve is one of big challenges since it can limit its potential large scale application by causing abnormal efficiency drop. Various studies have proposed different physical origins such as ferroelectric polarization, charge trapping/detrapping and ion migration, none of study has clearly explained the microscopic origin of the hysteretic behavior in MAPbI3-based perovskite solar cell. In this study, thus we have employed first-principles density functional theory calculations to identify the atomistic origin of hysteresis in MAPbI3. Our study has found that excess electrons or holes can stabilize two different Iodine Frenkel defect structures in MAPbI3. Since excess charge carriers can be easily accumulated near the electrode interface, the formation of two different Iodine Frenkel defects is inevitable and reversely it can act as a charge trap in MAPbI3-based solar cell. Thus, the hysteretic behavior of I-V curve is a result of charge trapping and detrapping during the formation of two types of Iodine Frenkel defects near electrodes. Based on our understanding, we have suggested several possible ways to suppressed the hysteresis in MAPbI3-based solar cell.