Semi-Transparent and Stable Solar Cells for Building Integrated Photovoltaics: The Confinement Effects of the Polymer Gel Electrolyte inside Mesoporous Films

The semi-transparent solar cells are promising to be applied in building integrated photovoltaic (BIPV) and tandem solar cells. In this study, we fabricate semi-transparent and stable solar cells for BIPV by utilizing a poly (ethylene oxide) electrolyte and controlling the size of TiO2 nanoparticles and the thickness of the TiO2 film. The power conversion efficiency of the semi-transparent (over 50% transmittance at 620-750 nm) and quasi-solid solar cells is 5.78% under standard AM1.5G, 100 mW cm-2. The higher conductivity and smaller diffusion resistance of the quasi-solid electrolyte inside the mesoporous TiO2 film indicate the confinement effects of the polymer electrolyte inside a mesoporous TiO2 film. The unsealed semi-transparent and quasi-solid solar cell retains its initial efficiency during 1000 h irradiation in humid air.