The present study was based on the optical, electrical, and DFT studies of ternary compounds. The host material was SnO2 and SnO2-Fe. The Fe doping was kept fixed at 2%. Cu in different percentages were doped with SnO2-Fe. The structural properties reveal the size of the nanoparticles can be engineered with Cu-doping variation. The optical studies by photoluminescence, UV-visible, and FTIR spectroscopy throw light on the application of the material as a visible-light photocatalyst. The shift in the absorption peak and change in the band gap with Cu was observed in the synthesized samples. The synthesized sample may also hold application in gas sensing because of oxygen vacancies created as observed in Raman spectra. The impedance study and DFT study explored the electrical behavior. With the increase in temperature, the conductivity of the sample is observed to decrease. The incorporation of Cu in SnO2-Fe reduces the impedance with its increasing concentration. The modification in the structure brought about an appreciable change in the Fermi level of SnO2 which can be decisive in the construction of ternary compound-based electronics.