Study of perovskite solar cells based on mixed-organic-cation FA(x)MA(1-x)PbI(3) absorption layer

摘要

Mixed-organic-cation FA(x)MA(1-x)PbI(3) films were prepared using a one-step solution deposition method in ambient air. The formamidinium (FA(+)) fraction 'x' was varied from 0.1 to 1 by changing the amounts of formamidinium iodide (FAI) and methylammonium iodide (MAI) in the precursor solution. Perovskite solar cells (PSCs) with a structure of FTO glass/compact TiO2/mesoporous TiO2/FA(x)MA(1-x)PbI(3)/carbon electrode were designed and fabricated. The effects of the FA(+) fraction 'x' on the structure, morphology and optical properties of the FA(x)MA(1-x)PbI(3) films as well as the photovoltaic performance of PSCs were studied. The results showed that the photovoltaic inactive delta-phase FAPbI(3) can be formed in the presence of high contents of FA(+) (x = 0.8 and 1.0). The band gap of FA(x)MA(1-x)PbI(3) decreased from 1.58 eV to 1.49 eV when the FA(+) fraction x increased from 0.1 to 1. The PSCs based on FA(0.4)MA(0.6)PbI(3) exhibited an optimal photovoltaic performance, yielding V-oc of 0.8 V, J(sc) of 22.84 mA cm(-2), FF of 0.48 and PCE of 8.77%.