Enhanced the efficiency and current density by structural modifications and conduction band shifting in lead-based mixed halide perovskite solar cells

Abstract

The pure and Mn-doped CsPbIBr₂ perovskite films are synthesized by sol-gel spin coating. X-ray diffraction (XRD) of pure and Mn-doped films shows the pure cubic perovskite phase in both samples, with Mn-doped samples having higher crystallinity and bigger crystal sizes (21.7–35.9 nm). Mn-doping induces lattice modifications, influencing the material's structural homogeneity and optoelectronic properties. UV–Vis spectroscopy elucidates the energy band gaps, showcasing a reduced bandgap (2.141–2.079 eV) in Mn-doped CsPbIBr₂. The J-V measurement of the device with configuration FTO\TiO₂\Mn-CsPbIBr₂\HTL\Au shows an efficiency of 10.42 %. To further improve the device performance, we use Mn-WO₃ ETL with TiO₂. XRD and Raman spectroscopic characterization declared a significant crystallinity of the 4 % Mn-WO₃ electron transport layer in monoclinic phase. The UV–vis spectroscopy analysis of Mn-WO3 fabricated which has wider bandgap promote charge carrier mobility and stability, whereas, low refractive index and dielectric constants decrease light reflection and absorption losses, thus solar cells efficiency improved. The current-density voltage (J-V) measurement of the final device with configuration FTO\TiO₂\Mn-WO₃\Mn-CsPbIBr₂\HTL\Au shows the efficiency of 12.75 % owing to better charge carrier extraction and decreased recombination losses. This in-depth review elucidates the origins of losses in perovskite solar cells and highlights the scope of improving efficiency by engineering materials and devices.