Copper Indium Sulfur Liquid-phase Reflux Method For Nano Powder And Its Photovoltaic Properties

CIS-based thin film solar cell (including CuInS2, CuInSe2, CuIn(SexS1-x)2, and so on) is one of the most promising thin film solar cells because of its high absorption coefficient and conversion efficiency, stable performance, excellent anti-jamming ability and anti-radiation. But this type of solar cells has a bottleneck in mass production for that the preparation technology of CIS-based absorption layer is very complicated and less of controllable. In this paper, using metal’s chloride and S/Se powders as starting materials, CIS-based powders were synthesized by liquid reflux method in appropriate solvent. The preparation technology of low cost and high quality CIS-based powders with mass production was investigated. It provides a new approach to the simple, controlled and low-cost preparation technology of CIS-based thin film solar cells. The main works and obtained results can be summarized as follows:(1) With the solvent of triethylenetetramine, triethylenetetramine-ethylene glycol (1:1, v/v), ethylenediamine-ethylene glycol (1:1, v/v) respectively, CuInS2powders were synthesized by liquid reflux method; Morphology, structure, phase constituents and optical properties of the as-prepared CuInS2powders in different solvents were investigated. The results show that the pure CuInS2powders with good stoichiometric composition can be synthesized in triethylenetetramine-ethylene glycol and ethylenediamine-ethylene glycol, respectively. Ethylene glycol can be used as the capping agent for the formation of particles with relatively dispersed size. Their energy band gaps of powders synthesized in triethylenetetramine-ethylene glycol were1.52eV, which matches well with the solar spectrum. Based on morphology, structure, phase constituents and optical properties, the mixed solvent of triethylenetetramine-ethylene glycol is the proper condition in preparing CuInS2powders.(2) With a mixed solvent of triethylenetetramine-ethylene glycol, the effects of technology conditions on morphology, structure, phase constituents and optical properties of the as-prepared CuInS2were investigated. The results show that the refluxing temperature affects phase constituents and optical properties of products greatly that rising the refluxing temperature is helpful for the improvement of crystallinity and well performance in their optical properties; The refluxing time produces little influence on morphology, structure, and phase constituents of the as-prepared CuInS2, but in a relatively short time (t<1h), their energy band gaps are too small, possessing the poor performance in their optical properties;200℃/2h is the proper condition in preparing CuInS2powders; The strong chelation and reduction properties of triethylenetetramine is the key point to synthesize CuInS2powders.(3) With a mixed solvent of triethylenetetramine-ethylene glycol, the influence of Se contents on morphology, structure, phase constituent and photoelectric properties of the as-prepared CuInS2was further studied. The results show that CuIn(SexS1-x)2powders can be prepared in the mixed solvent of triethylenetetramine-ethylene glycol with stoichiometric composition closely followed originally mixing ratio; With the increasing of Se content, the particle sizes enlarge gradually, producing the needlelike microstructures on the surface; Their energy band gaps can be changed by Se dopant that with the increasing of Se-doped content, the energy band gaps of products reduce; Meanwhile, Se dopant can makes the conduction type of CuInS2change from N type to P type.