Enhanced photovoltaic performance and reduced hysteresis in perovskite-ICBA-based solar cells

Abstract In this work, fullerene derivatives (ICBA and PCBM) are dissolved into perovskite precursors, and the corresponding perovskite solar cells are fabricated. Compared to PCBM, ICBA has better solubility in perovskite precursor solution (DMF). The added small amount of ICBA filled the vacancies at the grain boundaries of perovskite, and produced continuous pathways for electron extraction to enhance performance. Steady-state and time-resolved photoluminescence, together with the impedance measurements confirm the enhanced electron transporting property in perovskite-ICBA film. An excellent PCE of 18.14% is achieved in CH3NH3PbI3-xClx-ICBA-based solar cells with significantly suppressed hysteresis. Poor solubility of PCBM leads to a low concentration of PCBM in perovskite precursor, and results in a moderate PCE of 16.54% in device containing Perovskite-PCBM. By contrast, device based on pristine perovskite shows an inferior efficiency of 15.49% with large hysteresis. PSCs prepared from perovskite-ICBA with large area (1.12 cm2) are also fabricated, exhibiting a PCE of 13.69%. Results demonstrate that the strategy of dissolving ICBA into perovskite precursor directly is an efficient and facile way to improve PSCs performance as well as to reduce hysteresis.