Impact of Sb-insertion on structural, optical, and dielectric characteristics of the PbI<inf>2</inf> thin film

Abstract

Antimony (Sb) has been widely used as an additive in solar cells for enhanced performance. We described a simple, affordable, solution-processed approach for producing pure and antimony (Sb3+)-doped lead iodide (PbI2) thin films with varying doping ratios (0.5, 1.0, 2.0, and 3.0%). Structural, optical, and dielectric properties were investigated using XRD and UV–Vis spectroscopy. The XRD spectra illustrated that the synthesized PbI2 thin films have a preferred orientation along the c-axis (001) with a hexagonal structure. The crystalline sizes of PbI2 increased by increasing the Sb-doping concentration up to 1%, then decreased with 2% and 3% Sb-doping. In the visible and NIR regions, the optical transparency of the grown films were in between 70 and 80%. The optical band gap changes inversely with the crystalline sizes; it decreases with 0.5% and 1% Sb-doping and increases with further doping. As the energy gap is spanned between 2.39 and 2.27 eV, therefore, Sb: PbI2 films are ideal for use in solar cells. The resulting refractive index values were found to rise as the Sb doping concentration increased. Sb-doping decreases optical conductivity and dielectric constant.