Enhancing the thermoelectric properties of CZTS thin films grown on multi-crystalline Si substrate by controlling the sulfurization time duration

In this manuscript, we have reported the high value of the power factor for Copper Zinc Tin Sulfide (CZTS) thin films. CZTS samples used in this study were grown by a sol-gel method using spin coater on multi-crystalline Si (m-Si) substrate. After growth, effect of sulfurization time duration was tested by annealing the samples in the sulfur environment for different time durations (30-60 minutes) with a step of 10 minutes. The highest values of Seebeck (980 mu V/C-0), electrical conductivity (830 S/m) and power factor (7.88 x 10(-2) Wm(-1)K(-2)) were obtained for 60 minutes sulfurized sample. This enhancement in thermoelectric properties was related to the improvement of CZTS crystal structure due to increase by sulfurization time. The improvement in the crystal structure was supported by XRD and Raman spectroscopy measurements. XRD data demonstrated that a major CZTS (112) plane was observed at 2 circle minus=28.7 degrees for all samples. Crystalline size of grown samples was found to be increased from 12.92 nm to 14.9 nm with increasing the sulfurization time duration. Raman spectroscopy data also suggested that intensity of CZTS related active modes increased and the number of secondary phases decreased by increasing sulfurization time duration.