Hybrid inorganic-organic MAPbI3 (where MA denotes the CH3NH3 cation) or pure inorganic (CsSnI3 or CsPbI3) are intensively used for fabricating the perovskite solar cell because of its high efficiency and easy fabrication process. In this work, we are interested on using inorganic CsSnxPb1-xI3 films as the p-type transporting layer in the solid-state dye-sensitized solar cells (S-DSSCs). This is because the inorganic CsSnxPb1-xI3 perovskite film is the non-volatile and has the simple preparing process. Interesting, the efficiency of CsSnI3 based S-DSSCs has been reported to be very high of ~10.2% . The reason of the superior performance is due to the high hole mobility in CsSnI3 films (585 cm2V-1s-1 at room temperature). CsPbI3film also shows the p-type behavior, and it was successfully used as the light absorber with the goodcell efficiency of 2.9%  and 4.13% . The physical and optical properties of inorganic CsSnxPb1-xI3 films are depended on the ratio of Sn/Pb. In this work, CsSnxPb1-xI3 films were prepared by simply dropping the mixed CsI, SnI2 and PbI2solutions at five different Sn/Pb ratios (x = 1, 0.8, 0.5, 0.2 and 0) on the substrate surface. The color of CsSnxPb1-xI3 films was varied with the Sn/Pb ratio. The Sn/Pb ratio of 0.5, CsSn0.5Pb0.5I3, dictatesthe darkest color, whereas the other Sn/Pb ratios display dark-brown or yellow-like colors.The film morphology and crystallite will be analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Solid-state dye-sensitized solar cells (S-DSSC) were assembled by directly dropping the mixed CsI, SnI2 and PbI2 solution on the TiO2-coated-dye electrodes,anddryingunder the room temperature. CsSn0.5Pb0.5I3 based S-DSSC generates the highest efficiency of 3.47% amount all five conditions (CsSnxPb1-xI3, x = 1, 0.8, 0.5, 0.2 and 0). The cell impedances will be tested by Electrochemical Impedance Spectroscopy (EIS) for explaining the cell behaviors.
Principal Investigator: Associate Professor Dr. Vittaya Amornkitbamrung 1)