| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 101 === In this study, Cu2ZnSnS4 (CZTS) semiconductor thin films were deposited onto soda-lime glass substrates and indium-tin-oxide (ITO) coated glass substrates using the sulfurization of direct-current (DC) magnetron sputtered CuSn/Zn metal precursor. The effect of Cu/(Zn+Sn) molar ratio in samples on the structural, optical, and electrical properties of the samples was investigated. The application of solar energy using CZTS thin films was also examined.
X-ray diffraction patterns (XRD), energy dispersive analysis of X-ray (EDAX) and Raman spectrometer revealed that samples had the impurity such as Cubic-Cu2SnS3 phase in Cu-rich samples. With an increase in the content of Zn in CZTS thin films, the Kesterite CZTS phase was observed. Field-emission scanning electron microscope (FESEM) and atomic force microscope (AFM) images showed that island microstructures on the surface of samples became larger with the decrease of Cu/(Zn+Sn) molar ratio in samples. The roughness of samples decreased with the decrease of Cu/(Zn+Sn) molar ratio in samples. The thicknesses and direct band gaps of the CZTS samples were about 1.5 μm and in the range of 1.28 to 1.55 eV , respectively. From the Hall measurement results, the carrier concentrations and resistivity of samples decreased and increased with a decrease in Cu/(Zn+Sn) molar ratios in samples. The conduction type of samples on glass substrates were p-type semiconductors. Maximum photo-enhancement current density of samples reached to 0.54 mA/cm2 with the external bias kept at -0.6 V vs. Ag/AgCl reference electrode in the aqueous pH=0.5 H2SO4 solution .
In solar energy application, thin films CZTS solar cell showed the best efficiency of 0.028 % (Voc=0.02 V,Jsc= 0.15mA/cm2,FF=0.195) and the dye sensitized solar cell with the structure of TiO2/N719/I-/I3-/CZTS had the maximum solar conversion efficiency of 8.49 %( Voc=778.20 mV,Jsc=16.33 mA/cm2,FF=0.67) under AM 1.5 solar irradiation.
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