## 3 Results and Discussion
However, the main peak shifted from 329.281 to 334.345 cm\({}^{-1}\), and the decrease in FWHM from 28.837 to 13.318 indicates improved crystallinity of the films with increasing energy application. The elemental compositions of these films were obtained by EDS analyses, as summarized in Tables 1 and 2. The various treatment conditions of the CZTS thin samples present a Cu-poor and Zn-rich composition with ratios of Cu/(Zn + Sn) and Zn/Sn, which are important for improving inter-diffusion in the precursor and improving the optoelectronic properties for high performance [23; 24]. The dominant composition ratio occurs at 2.96 J/cm\({}^{2}\). Increasing the bank voltage changed the composition as well as the performance of CZTS solar cells. Figure 4: XRD patterns of photo-sintered CZTS thin films on molybdenum glass substrate. Figure 5: Raman spectrum of photo-sintered CZTS thin films on molybdenum glass substrate. To analyze the performance of the applied photo-sintered film, the solar cell device was fabricated with the layer of Glass/Mo/CZTS/CdS/i-ZNO/AZO/Al. The overall fabrication process is provided in Figure 6 and the photocurrent density versus voltage (J-V) plot and performance of the photo-sintered CZTS solar cell are presented in Figure 7 and Table 3. The device with the photo-sintered CZTS film displayed a photovoltaic response, which has an energy density of 2.96 J/cm\({}^{2}\), and exhibited the efficiency of 1.01% with an open circuit voltage (Voc) of 0.214 V, short circuit current density (Jsc) of 5.913 mA/cm\({}^{2}\), and fill factor of 32.789%. These results clearly indicate that the light irradiation practically sintered the coated CZTS film. Using the sulfurized CZTS film, more than 10% of the efficiency were reported [25; 26; 27; 28]; therefore, further research on applying the photo-sintering technique is required to replace the conventional thermal annealing process. [PERSON] et al. have demonstrated that the temperature of the annealing process for CZTS film can affect the efficiency of the solar cell [29]. By controlling the light intensity and dosage, a more optimized grain size can be achieved and this may lead to high efficiency of the photo-sintered CZTS solar cell device. \begin{table}
\begin{tabular}{c c c} \hline
**Condition** & **Peak (cm\({}^{-1}\))** & **FWHM** \\ \hline As-coated & 329.281 & 28.837 \\
2.82 J/cm\({}^{2}\) & 331.307 & 22.333 \\
2.96 J/cm\({}^{2}\) & 333.838 & 13.642 \\
3.09 J/cm\({}^{2}\) & 334.345 & 13.318 \\ \hline \end{tabular}
\end{table} 
Table 1: Raman analysis of photo-sintered CZTS thin films at the highest peak positions. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Treatment** & \multicolumn{4}{c}{**Elemental Component (at\%)**} & \multicolumn{4}{c}{**Composition Ratio (at\%)**} \\
**Condition** & **S** & **Sn** & **Cu** & **Zn** & **Cu/(Zn + Sn)** & **Zn/Sn** & **Cu/Sn** & **S/Metal** \\ \hline As-coated & 47.35 & 25.56 & 17.77 & 9.32 & 0.943 & 1.906 & 2.742 & 0.899 \\
2.82 J/cm\({}^{2}\) & 47.88 & 24.7 & 16.24 & 11.18 & 0.900 & 1.452 & 2.209 & 0.918 \\
2.96 J/cm\({}^{2}\) & 46.46 & 24.66 & 17.88 & 11.01 & 0.853 & 1.623 & 2.239 & 0.867 \\
3.09 J/cm\({}^{2}\) & 47.54 & 23.01 & 16.98 & 12.46 & 0.781 & 1.362 & 1.846 & 0.906 \\ \hline \end{tabular}
\end{table} 
Table 2: Chemical composition and composition ratios. Figure 6: Schematic of the CZTS solar cell fabrication process.