Suppressed J-V hysteresis in highly efficient inverted perovskite solar cells using small-molecule non-fullerene acceptor

Perovskite has attracted enormous research interest due to the unique advantages, such as high absorption coefficient, great carrier mobility, low exciton binding energy, etc., providing desirable applications in high-performance perovskite solar cells (PSCs). However, the current density-voltage (J-V) hysteresis phenomenon in PSC will reduce the testing accuracy and weaken the actual device performance. In this paper, a facile method based on interfacial engineering is proposed to suppress the hysteresis phenomenon and the deeper physicochemical mechanism is systematically analyzed. By incorporating non-fullerene acceptor Y6 in the crystallization process, a denser and continuous perovskite film with a low-density defect state is obtained, which affords PSC dramatically suppressed the J-V hysteresis with the hysteresis difference decreasing from 13.6% to 1.9% at the maximum power point. Furthermore, scanning electron microscope results and energy dispersive spectrum mappings suggest that ultrathin Y6 film is deposited between the perovskite film and the hydrophobic electron transport layer of PC61BM. The improvement of wettability and matching energy level caused by Y6, render the photocurrent increase and the power conversion efficiency of PSC@Y6 high up to 17.5%. Thus, this work demonstrates that interfacial engineering using small-molecule non-fullerene acceptor is a promising strategy to suppress the J-V hysteresis limiting further PSC commercialization.