Perovskite Film Passivated by Fmoc-FF-OH and Its Photovoltaic Performance

Organic-inorganic hybrid perovskite is an ideal light absorption material due to its high light absorption coefficient, adjustable band gap and bipolar charge conduction characteristics. However, perovskite thin films prepared by solution method possess various defects in the surface and interface, which inhibit carrier transport and trigger recombination. In this study, a multifunctional amino acid derivative, 9-fluorenylmethoxycarbonylL-phenylalanine-L-phenylalanine（Fmoc-FF-OH）, was selected as an additive to reduce defects of perovskite film and to inhibit carrier recombination at grain boundaries. When the concentration of Fmoc-FF-OH is 0.6 g·L-1, the particle size of the perovskite thin film increases from 138 to 210 nm, and the defect state density decreases from 2.46×1015 to 2.17×1015 cm-3. Perovskite solar cells also exhibit optimal performance with open circuit voltage increasing from 1.05 to 1.10 V, and photoelectric conversion efficiency （ PCE ） improved from 15.50% to 17.44%.After stability test f