Preparation Of Copper - Zinc - Sn - S Thin Film Materials And Solar Cells By Sputtering

The Cu2 Zn Sn(S,Se)4 thin film solar cells have some obvious merits including high conversion efficiency, economized raw material and simple production process. The quality of CZTS film mainly depends on the preparation conditions. Combining with the corresponding theory, the impacts of preparation condition on CZTS films and cells were discussed in this work.The Cu2 Zn Sn(S,Se)4(CZTSSe) films were prepared by sputtering and post annealing, and the cell devices based on the as-prepared CZTS or CZTSe film were fabricated by sequentially depositing buffer layer and window layer. The morphology, structure, composition and optical-electrical properties of the CZTS films were characterized by scanning electron microscope(SEM), X-ray diffraction, Energy Dispersive X-ray spectrometers, UV-vis spectrophotometer and Hall measurement, respectively. Finally, the performance of as-prepared CZTS cell devices was demonstrated by I-V curve.The main research contents in this work include:(1) The impacts of temperature during sulfurization on grain sizes were researched.(2)The relation between the Sn-lose and the morphologies of CZTS film was confirmed.(3) The influences of heating rate during sulfurization on flatness, compactness and grain size were investigated in detail.(4)The relation between the sputtering order of metallic precursor(stacking order) and characters of CZTS film was studied.(5)The effect of different stacking order of sulfur-containing precursor on CZTS films was investigated.(6) The selenization process of precursor was studied by referring the sufurization process.(7) The optical and electrical characteristics of well-chosen CZTS films were characterized by UV-vis spectrophotometer and Hall system.(8) TheCZTS(Se) cells based on well-chosen CZTS films were fabricated by depositing Cd S buffer layer and i-Zn Oand AZO window layer.(9) The performance of CZTS(Se) cells were measured and analyzed by I-V measurement.The researching results showed that:(1) A high sulfurization temperature can improve the grain sizes.(2) A high sulfurization temperature can accelerate the Sn-loss that lead to the formation of Cu2-x S secondary phase and many concavities.(3) The Sn-loss can be compensated by prolonging the sputtering time of Sn taget.(4) A suitable heating rate during 300 ℃-480 ℃ is crucial to the flatness of CZTS films.(5) There is no obvious CZTS film characteristical difference between different stacking order.(6) The different stacking order of sulfur-conntaining precursors can not obviously influence the morphologies of CZTS films.(7) The CZTS(Se) cells with above 2.0%efficiency were measured by I-V system.(8) The high series resistance of CZTS(Se) cells was caused probably by thick Mo S2 layer between the Mo substrate and CZTS(Se) films., CZTS/Cd S interface and window layer with low conductivity.