Enhancing efficiency of Cs2AgBiBr6 double perovskite solar cells through bandgap reduction by molybdenum doping

The thin films of molybdenum (Mo) doped Cs2AgBiBr6 lead-free halide double perovskite solar cells (LFHDPs), were synthesized through a sol–gel method. X-ray diffraction (XRD), UV–Vis spectroscopy, and J–V analysis were used to thoroughly examine the structural, optical, and electrical properties, respectively. XRD confirmed a cubic structure, with Mo doping increasing grain size. UV–Vis spectroscopy indicated a reduced bandgap energy (Eg) to 1.86 eV and a refractive index increase to 2.77. The solar cells fabricated with these films and compared their efficiency. The geometry of the cell is Au/Spiro-OMeTAD/Cs2AgBiBr6/TiO2/FTO/glass. The fabricated Mo-doped solar cell exhibited improved parameters: short circuit current (JSC) of 5.59 mA-cm−2, fill factor (FF) of 0.755, open circuit voltage (VOC) of 0.936 V, and efficiency (η) of 3.95%. This η is 25.39% increased over pristine Cs2AgBiBr6. This comprehensive characterization suggests that Mo-doped Cs2AgBiBr6 thin films hold the potential for enhanced photovoltaic performance in solar cell applications.