Flexible Dye-Sensitized Solar Cells Assisted with Lead-Free Perovskite Halide

Dye-sensitized solar cells (DSSCs) have shown promising alternative to Si-based counterparts due to low cost, abundant raw materials, and non-vacuum processing. Here, we report a solution-based process to create flexible DSSCs on aluminum foils. Mesoporous TiO₂ electrode was directly deposited on Al foil through spin casting. After post-thermal annealing, the resultant samples render optical smooth, crack-free, and large nanocrystalline thin films. The as-prepared double-layer porous TiO₂ thin film was incorporated with a porphyrin dye followed by a perovskite halide salt Cs₂SnI₆, as the hole transport material, replacing liquid electrolyte. A transparent conducting plastic sheet was used as the cathodic electrode to complete the solar cell construction. Samples were characterized using X-ray diffraction, SEM, AFM, UV-Vis spectrometer, and current-voltage measurements. A photo-electricity conversion efficiency of 3.74% has been achieved that potentially makes the possibility of scaling up fabrication of all-solid-state flexible solar cells.