Synthesis of diamond-like carbon films by electro-deposition technique for solar cell applications

High transparent diamond-like carbon (DLC) films were deposited on ITO and silicon substrates by electro-deposition technique using a mixture of methanol and ethanol as electrolyte. The effect of varying of ethanol and methanol volume ratios on optical and structural properties of electrodeposited DLC films was investigated. The increase of methanol volume ratio resulted to an increase in the SP3 content. The optical band gap of the DLC films was found to be in the range of (1.75-2.15) eV. The refractive index of films ranged from 1.19 to 1.39 at the wavelength of 600 nm. The experimental data showed that the best DLC film has an average reflectance less than 4.5 % in the visible region. The efficiency of the silicon solar cells increased from 4.5 to 5.88 % after depositing a 70 nm thick, single antireflection DLC film. The open circuit voltage Voc, short circuit current density Jsc and spectral responsivity of solar cells were investigated as function of DLC film thickness.