Effects of sulfurization time and H2S concentration on electrical properties of Cu2ZnSnS4 films prepared by sol–gel method

•Cu2ZnSnS4 (CZTS) films were prepared by sol–gel method following sulfurization.•The sulfurization time and H2S concentration have the effects on the electrical properties.•The tin loss is increased with the increasing of the sulfurization time.•The secondary phases like ZnS make the electrical properties worse.•The CZTS films sulfurized at 5% H2S for 90 min had the best electrical properties.

Cu2ZnSnS4 (CZTS) thin films have been successfully deposited by a sol–gel method and sulfurization process. The properties of the films were investigated by varying sulfurization time and H2S concentration. X-ray diffraction and Raman spectra analyses revealed the formation of CZTS films with a tetragonal type kesterite structure. With increasing the sulfurization time and H2S concentration, the intensity of the kesterite (1 1 2) peak became sharper. The stoichiometric ratios of the CZTS films were different from the precursors, which was due to Sn loss during the sulfurization process. The electrical resistivity and mobility of the films increased while the carrier concentration decreased with increasing the sulfurization time. The CZTS thin films sulfurized at 5% H2S concentration for 90 min had the best opto-electrical properties with Eg of 1.41 eV, resistivity of 3.64 Ω cm, carrier concentration of 1.11 × 1018 cm−3 and mobility of 1.54 cm2/(V s) at room temperature for PV application.

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