Microwave-assisted Fe-doped ZnO nanoparticles for enhancement of silicon solar cell efficiency

We have investigated the performance of a silicon solar cell coated with ZnO nanoparticle layers doped with iron varying from (0-20%). We synthesized nanoparticles using a microwave method and fabricated thin film layers on silicon solar cells through a spin coating technique. The structure and morphology of nanoparticles were analyzed through transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). The size of the particles decreased as iron concentration increased from 0 to 15%. Optical properties were analyzed through photoluminescence (PL) and absorption spectroscopy. PL spectra show a blueshift in the near band edge emission peaks for 0-15% doped samples and a redshift for the 20% doped sample. The band gap of Fe-ZnO nanoparticles (0-15%) was found to increase from 3.20 eV to 3.24 eV, and the bandgap decreased to 3.22 eV for 20% Fe-ZnO nanoparticles. Current-Voltage measurements confirm the enhancement in power conversion efficiency by 30% with iron doping in ZnO up to 15%. Efficiency increased with nanoparticle layers up to 180.29 nm in every sample and decreased with further increase in thickness. Enhancement in external quantum efficiency (EQE) was also observed with the increase in dopant concentration up to 15%. The optimum thickness of the ZnO nanoparticle layer was found to be approximately 180 nm for maximum enhancement in conversion efficiency.