Efficiency enhancement of nano structured Cu2O:Ag/laser etched silicon-thin films fabricated via vacuum thermal evaporation technique for solar cell application

Among the metal oxide semiconductor-based solar cells, cuprous oxide (Cu2O) thin films as an active layer possess interesting physical and chemical properties. In the present work, pure and Ag-doped thin films of Cu2O were deposited on laser-etched silicon substrates via thermal evaporation technique under vacuum, with minimal ratios of silver doping (0.02, 0.04, and 0.06) wt% and average thickness of 60 nm. X-ray diffraction results revealed that the fabricated films were polycrystalline with a cubic structure and preferential orientation in the (111) direction. There are no characteristic peaks for the silver due to the low doping ratios. FESEM images of pure and Cu2O:Ag films revealed that the films had a certain smooth surface consisting of compact clusters of fine grains. The AFM images of the films show a uniform granular surface morphology with the topography that is similar in most of the surfaces of the prepared films due to the vacuum deposition. The results of optical properties revealed a decrease in the transmittance spectra as the silver content increased. The fabricated thin films (pure and Ag-doped) exhibited a direct energy gap (E-g) that decreased from 3.5 to 3 eV as the Ag doping increased. The I-V characteristic results revealed a promising increase in the conversion efficiency of the fabricated solar cell to 6.48% with short circuit current (I-sc) of 4.7 mA, open-circuit voltage (V-oc) of 3.8 V, and filling factor (F.F) of 0.335 at P = 100 mW/cm(2).