Reduced recombination losses and enhanced charge carrier extraction within scandium doped perovskite film through an energy alignment of the conduction band of ETL with perovskite film

This study presents a novel approach for improving the efficiency of lead-based mixed halides perovskite solar cell (PSC) by Scandium (Sc) doping with the perovskite layer and creating a dual electron transport layer (ETL) using TiO₂ and Sc-doped WO₃. The cubic structure of perovskites was verified by X-ray diffraction (XRD), and UV–Vis absorption spectra showed a red shift with reduced energy band gap (E_g) from 1.932 eV to 1.926 eV. The single TiO₂\CsPbIBr₂-based device showed a power conversion efficiency (PCE) of 9.53 %, which was enhanced up to 10.12 % by utilizing Sc-CsPbIBr₂. To further enhance the performance of the device, 4 % Sc-WO₃ film was deposited between TiO₂ and perovskite. The monoclinic structure of Sc-WO₃ was confirmed by the XRD with the E_g of 2.741 eV. Raman peaks showed the W–O–W stretching vibrations and terminal WO bonds. A PCE of 11.72 % was attained by configuration (TiO₂\Sc-WO₃\CsPbIBr₂\Spiro-OMeTAD\Au), and this was further enhanced to 13.64 % for the configuration (TiO₂\Sc-WO₃\Sc-CsPbIBr₂\Spiro-OMeTAD\Au). Electrochemical impedance spectroscopy (EIS) analysis revealed that the optimized device had better charge transfer and reduced recombination resistance with the stability maintained 90.11 % of its initial PCE, demonstrating exceptional stability. These results show that Sc-doping and dual ETLs successfully improves PSC stability and performance, providing a viable path for next-generation solar cell technology.