A discussion on the origin and solutions of hysteresis in perovskite hybrid solar cells

Although the record efficiencies of perovskite hybrid solar cells are gradually reaching the efficiency of crystalline Si solar cells, perovskite hybrid solar cells often exhibit significant current density–voltage (J–V) hysteresis with respect to the forward and reverse scan direction and scan rate. The origin of the J–V hysteresis of perovskite hybrid solar cells has not, to date, been clearly elucidated. Dielectric polarization by the ferroelectric properties of perovskite (i), the ionic motion/migration of perovskite materials (ii), and charge trapping and detrapping at trap sites by the unbalanced electron and hole flux (iii) are considered the possible origins of J–V hysteresis. Here, we reviewed the origin of the J–V hysteresis of perovskite solar cells from the above three points of view and we then suggest how one may reduce the J–V hysteresis with respect to the scan direction and scan rate.