Structure and optical characterization of earth abundant Cu2MSn(S,Se)4 and ZnO1-xSx layers for thin film solar cell

• Main Author: Lie, Stener
• Other Authors: Lydia Helena Wong
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Materials::Energy materials
• Online Access: http://hdl.handle.net/10356/62498
• Institution: Nanyang Technological University

Investigation on the crystal structure and optical properties of Cu2MSn(S,Se)4 and ZnO1-xSx layers were conducted to study their viability as absorber and buffer layers for thin film solar cell respectively. Cu2M(Metal)SnS4 thin films were successfully fabricated on Molybdenum-coated glass by chemical spray pyrolysis (CSP) technique with variation of Metal (Mg, Mn and Ni). The precursor used was a mixture of metal ion Chlorides and Thiourea with fixed ratio. The pyrolysis was done in atmospheric condition with hotplate temperature 450oC. This was followed by a selenization process with temperature 520oC for 12 minutes. X-ray Diffraction (XRD), Raman Spectroscopy and ultraviolet-visible light spectroscopy (UV-Vis) were done to investigate the crystal structure and band gap of the compounds and act as premises to select the compound to focus for fabricating thin film solar cells. Energy-dispersive X-ray spectroscopy (EDX) was done to verify the purity and elemental composition of Cu2MnSn(S,Se)4. Cu2MnSn(S,Se)4 are promising owing to its purity and low band gap. Following that, a study on selenization temperature dependency was done to study its effect on the crystal structure and band gap with three different temperatures, 460oC, 500oC and 540oC. The result shows a better crystallinity and lower band gap value for higher temperature. The J-V curve of the three samples were also measured using solar simulator. The efficiency achieved was around 0.0001%. In the second part of the report, ZnO1-xSx layer were also successfully deposited on glass by chemical spray pyrolysis (CSP) with variation 0 < x < 1. The precursor used was a mixture of Zinc Chloride (ZnCl2) and Thioacetamide. The pyrolysis was done in atmospheric condition with hotplate temperature 450oC. EDX shows a decreasing trend of incorporated Sulphur in thin film as Sulphur ratio in solution increase. Characterization by XRD shows the structural transformation from ZnO peaks domination to ZnS peaks domination with anomaly occurs in the middle. Optical band-gap energy of ZnO1-xSx ¬¬film trend measured by UV-Vis follows the band gap of the dominant structure with slight variation and very high band gap in the middle.