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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