Fullerene derivative as an additive for highly efficient printable mesoscopic perovskite solar cells

Abstract By introducing [6,6]-phenyl-C 61 -butyric acid methyl ester as an effective additive in the perovskite precursor solution, we demonstrate a grain interface-engineering approach for universally increasing the efficiency of perovskite solar cells based on the printable triple mesoscopic structure of TiO 2 /ZrO 2 /carbon. These perovskite solar cells have advantages of low-cost and are easy to scale up, however the micrometer-thick mesoscopic layers and one-step dropping method challenge perovskite crystallization in such devices, resulting in non-ignorable charge-recombination loss. With adding an optimized 0.25 mg mL −1 PCBM into the perovskite precursor solution, we improve the champion PCE of PSCs using MAPbI 3 perovskites from 8.58% to 12.36% and that of PSCs using MAPbI 2.95 (BF 4 ) 0.05 perovskites from 12.77% to 14.26%. We find that the PCBM additive affects the perovskite morphology, facilitates the photo-generated charge separation and suppresses the charge recombination in the device, thus yielding a universal improvement of MPSC performance. This work gives a new insight towards designing high performance perovskite solar cells.