Efficiency boost in perovskite solar cells via TiO2 nanodiscs embedded in the MoSe2 electron transport layer revealed by optoelectronic simulations†

To improve the performance of inverted perovskite solar cells (IPSCs), we introduce a novel approach to enhance the devices' efficiency notably using the Finite Element Method (FEM). Our novel strategy incorporates a cutting-edge metasurface-based reflector featuring titanium dioxide (TiO₂) nanodiscs within a MoSe₂ layer, employed as an electron transport layer (ETL). Demonstrating a substantial improvement in light reflection from the lower part of the structure, the TiO₂ nanodiscs as a metasurface-based reflector enhance electron transfer. Notably, the metasurface-based perfect reflector, incorporating TiO₂ nanodiscs, outperforms other TiO₂ nanocube variations with an impressive light reflectance of 97.95%. Exploring different materials for ETLs and hole transfer layers (HTLs), we identify molybdenum diselenide (MoSe₂) as a potent secondary absorbent material, featuring a smaller bandgap than the primary absorbent CH₃NH₃PbI₃ (MAPbI₃), thereby intensifying the electric field within the active layer and improving Power Conversion Efficiency (PCE). In the final evaluation, our inverted metasurface-based device structure (indium tin oxide (ITO)/cuprous oxide (Cu₂O)/MAPbI₃/TiO₂ nanodiscs and MoSe₂/aluminum (Al)/silicon dioxide (SiO₂)) significantly enhances the solar cell's electrical characteristics compared to the planar reference structure (ITO/copper(I) thiocyanate (CuSCN)/MAPbI₃/TiO₂/Al), with noteworthy increases in short circuit current density (J_sc), open circuit voltage (V_oc), and PCE values from 17.98 mA cm⁻² to 21.91 mA cm⁻², 1.03 V to 1.07 V, and 15.33% to 19.17%, respectively. This comprehensive investigation underscores the promising potential of our proposed inverted metasurface-based device structure for advancing solar cell technology.