Effect of Ag doping on structural, optical, complex impedance and photovoltaic properties of SnO2 nanoparticles prepared by co-precipitation method for dye sensitized solar cell application

The pure SnO2 and Ag-doped snO2 nanoparticles (NPs) were prepared by co-precipitation method. The structural, electrical and optical properties of the material were systematically studied. The XRD patterns of both samples reveal that the presence of cassiterite tetragonal structure and GSAS fittings confirms the incorporation of Ag in SnO2 lattices. The SEM-EDS analysis reveals that the presence of spherical-shaped NPs with the expected elements. The Raman spectra of Ag-doped SnO2 NPs show that the two extra local disorder vibrational modes while comparing with pure SnO2. The UV-Vis spectroscopy result shows that the Ag doping reduces the optical band gap and increases Urbach tail energy with a reduced effective energy band gap in Ag-doped SnO2 NPs. The Photoluminescence spectrum confirms the presence of the defects like oxygen vacancies; however, these defects are increased by the Ag-doped SnO2 system. From the dielectric measurements, the conductivity of both samples followed Jonscher’s power law. The nonlinear least-square fittings on Nyquist plots of both samples suggested that the conduction process took place predominantly through grain boundary in SnO2 NPs whereas through grains in Ag-SnO2 NPs. This nature of band gap narrowing with increased conductivity in Ag-doped samples drives these samples for good solar cell activity applications. As expected, photovoltaic measurements show higher power conversion efficiency in Ag-doped SnO2 NPs. These results were discussed by correlating optical and dielectric properties of SnO2 and Ag-doped SnO2 NPs which gave a broad understanding for device fabrications successfully. •XRD, Raman, FTIR studies confirm the doping of Ag in Sn sites of SnO2 NPs.•UV and PL data confirm the red shift and the oxygen defects vacancies by Ag doping.•Ag doping reduces optical energy band gap but increases Urbach energy by the defects.•The nonlinear least square fitting on the Nyquist plots and Jonscher power law fitting on the AC conductivity plots.•The energy level of the pure and Ag doped SnO2 NPs with molecular structure of N719 dye and DSSC operation of Ag doped SnO2 photoanode.