Hexagonal mesoporous silica/perovskite oxides composites as unique scattering layers in photoelectrodes of high performance dye-sensitized photovoltaics

Abstract

As the photoactive TiO2 film in dye-sensitized solar cells (DSSCs) is transparent to incident light owing to its nano-sized particles, the efficiency may be affected by the light loss. Therefore, light scattering layers including CeMnO3, CeFeO3, CeSnO3, CeZnO3, 3D-hexagonal mesoporous silica (HMS-3), and HMS-3:CeMnO3 composites were deposited on TiO2 layer by doctor blade technique in order to harvest more sunlight. To characterize each material, XRD, FTIR, PL, DRS, FESEM, EDS, and BET analyses were investigated. In addition, dye absorption capacity, power conversion efficiency (PCE), open-circuit voltage decay (OCVD), and charge transfer parameters were assessed. According to photovoltaic data, TiO2/50 wt% HMS-3+50 wt% CeMnO3 based DSSC brought about the maximum PCE of 7.47% with fill factor (FF), short-circuit current density (Jsc), and open-circuit voltage (Voc) of 0.48, 21.17 mA/cm2, and 0.738 V, respectively, displaying 75.4% higher PCE compared to solar cell fabricated by TiO2 (PCE = 4.26%, Jsc = 11.72, Voc = 0.685 V, FF = 0.53). The champion 50 wt% HMS-3+50 wt% CeMnO3 composite featured large particles with high porosity, which could enhance light scattering and cause the light path to be longer, based on the Mie theory. Moreover, because of the big surface area (643.80 m2/g), large pore volume (0.4282 cm3/g), and appropriate N719 dye loading of the champion 50 wt% HMS-3+50 wt% CeMnO3 composite, more dye molecules were excited, and the number of light-generated electrons was boosted, elevating the current density, facilitating faster charge transfer from the TiO2 photoanode towards the Pt electrode, and limiting electron-hole recombination to a high extent, which led to an enormous improvement in efficiency.