Zinc and [Zinc, Nickel]: Co - doped SnO 2 nanoparticles as prospective electron transport layer materials for efficient lead free-MASnI 3 perovskite solar cells

In this study, we explore the potential of both pristine and doped tin oxide (SnO 2 ) as promising materials as the electron transport layer (ETL) for efficient lead free-methylammonium tin iodide (MASnI 3 ) perovskite solar cells (PSCs). The pristine, Zinc (Zn) doped, and Nickel (Ni)-Zn co-doped SnO 2 nanoparticles with a constant concentration of Zn while changing the concentration of Ni were synthesized by using the hydrothermal method. The effect of doping and co -doping on optical, structural, and electrical properties of SnO 2 nanoparticles was investigated using different microscopic and spectroscopic tools. The X-ray diffractograms showed that pristine, doped, and co-doped SnO 2 nanoparticles have better crystallinity and tetragonal rutile crystal structure. The fingerprint functional groups and elemental composition were confirmed by FTIR absorption peaks, EDX, and XPS, respectively. The UV -Vis DRS spectroscopy results revealed that the optical band gap reduced from 2.90 eV for pristine SnO 2 to 2.26 eV for co-doped 1 wt (wt) % Ni-Zn-SnO 2 nanoparticles and can be tuned with a variation of wt % of Ni. Further, the photoluminescence emissions of all SnO 2 nanoparticles in the range of 307 to 494 nm are related to oxygen vacancies or defects. Moreover, BET results confirms larger surface area for 1 wt % Ni-ZnSnO 2 , which can help in better electron-hole pair separation. The electrical conductivity studies confirm that the synthesized nanoparticles exhibit excellent ohmic contact behavior and show a notable increase in electrical conductivity for 1 wt% Ni-Zn-SnO 2 nanoparticles. Further, the suitability of both pristine and doped SnO 2 as ETL material for the MASnI 3 -based PSCs was simulated using SCAPS-1D software. The best power conversion efficiency of 29.60 % was achieved for FTO/1 wt % Ni-Zn-SnO 2 /MASnI 3 /Spiro-OMeTAD/Au. This investigation highlights the potential of co-doped materials as promising candidates for the development of efficient PSCs.