Effects of diethanolamine on sol–gel–processed Cu2ZnSnS4 photovoltaic absorber thin films

•DEA content significantly affected the crystal structure and the phase purity.•The films’ crystallite sizes increased with increasing DEA content.•Two different impurity levels were found for each film via R-T characteristics.•Under different illuminations, the n-Si/CZTS exhibited good photo-response.•The light on/off current ratios confirmed the photo-sensitivity of the junction.

As a promising solar absorber, the Cu2ZnSnS4 compound has been popular recently for the production of green and economical thin-film solar cells owing to the abundancy and non-toxicity of all the constituents. In this study, we have produced Cu2ZnSnS4 films via the sol–gel technique. As a stabilizer, the effects of the diethanolamine on the properties of the films were investigated. The amount of diethanolamine significantly affected the crystal structure, crystallite sizes and phase purity of the films. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. It was found that the film produced by using 2 ml of diethanolamine in sol exhibited pure CZTS phase, compact and dense morphology and enhanced photo-sensitivity. Light on/off current ratio of the n-Si/Cu2ZnSnS4 junction was found to be 47 under 100 mW/cm2 of illumination. Electrical activation energies of the films were investigated and the variations were attributed to delocalized phonon states generating from the presence of other phases and lattice defects.

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