Solvothermal Synthesis,Characterization And Optical Properties Of Cu₂?Fe,Zn??Ge,Sn?S₄ Series Nanocrystal Powders

Renewable energy exploitation is the only solution for energy and ecological environment problems.Solar energy is the uppermost reproducible energy for humankind,so the research of photovoltaic semiconductor has been a focus for researchers.The series materials of Cu₂?Fe,Zn??Ge,Sn?S₄ are important semiconductors for photovoltaic materials,and they are all widely used in the field of solar cells.Quaternary Cu₂ FeGeS₄,Cu₂FeSnS₄,Cu₂ZnGeS₄ and pentabasic Cu₂ Fe GexSn1-xS₄ nanocrystal powders were synthesized via solvothermal method in this paper.Structure,morphology,constituents and optical properties of as-prepared Cu₂?Fe,Zn??Ge,Sn?S₄ products were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,X-ray photoelectron spectroscopy?XPS?and UV-vis spectrophotometer?UV-Vis?.The main results are as follows:?1?Cu₂FeGeS₄ nanocrystal powder was successfully synthesized via solvothermal method using CuCl as copper source,FeCl₂·4H₂O as iron source,Ge Cl₄ as germanium source,L-cysteine,L-cystine as sulfur sources,dimethylformamide as solvent.The influence of reaction temperature,time and different sulfur sources on the products wereinvestigated.The results show that temperature and time have great influence on synthesis of Cu₂ Fe GeS₄ nanocrystal powder,the grain size increases gradually?10.8nm¹4.1nm?with the time prolonging?12h⁴8h?,temperature increasing?180?²20??;Compared with L-cystine,the phase of powder synthesized using L-cysteine as sulfur source is more pure under other same experiment conditions;The band gap of Cu₂ Fe GeS₄ nanocrystal powder obtained by UV-Vis is 1.7eV.?2?Cu₂FeSnS₄ nanocrystal powder was successfully synthesized via solvothermal method using CuCl as copper source,Fe Cl₂·4H₂O as iron source,SnCl₂·2H₂O as tin source,L-cysteine,L-cystine,thiourea as sulfur sources,dimethylformamide as solvent.The influence of reaction temperature,time and different sulfur sources on the products were investigated.The results show that temperature and time have great influence on synthesis of Cu₂ Fe Sn S₄ nanocrystal powder,the grain size increases gradually?14.9nm⁷5.5nm?with the time prolonging?12h⁴8h?,temperature increasing?180?²20??;Compared with L-cystine,thiourea,the phase of powder synthesized using L-cysteine as sulfur source is more pure under other same experiment conditions;The band gap of Cu₂FeGeS₄ nanocrystal powder obtained by UV-Vis is 1.5e V.?3?Cu₂ZnGeS₄ nanocrystal powder was successfully synthesized via solvothermal method using CuCl as copper source,ZnCl₂ as iron source,Ge Cl₄ as germanium source,L-cystine,L-cysteine as sulfur sources,dimethylformamide as solvent.The influence of reaction temperature,time and different sulfur sources on the products were investigated.The results show that temperature and time have great influence on synthesis of Cu₂ Zn Ge S₄ nanocrystal powder,the grain size increases gradually?10.4nm¹3.9nm?with the time prolonging?12h³6h?,temperature increasing?180?²20??;Compared with L-cysteine,the phase of powder synthesized using L-cystine as sulfur source is morepure under other same experiment conditions;The band gap of Cu₂ Zn Ge S₄ nanocrystal powder obtained by UV-Vis is 2.35 e V.?4?Cu₂FeGe_xSn_1-xS₄ nanocrystal powder was successfully synthesized via solvothermal method based on Cu₂ Fe GeS₄ nanocrystal powder and Cu₂ FeSn S₄ nanocrystal powder using CuCl as copper source,FeCl₂·4H₂O as iron source,Ge Cl₄ as germanium source,SnCl₂·2H₂O as tin source,dimethylformamide as solvent under 240? at 12 h.