Preparation And Characterization Of Cu₂ZnSnS₄and Cu₂NiSnS₄Research

Energy crisis and environmental pollution make solar cells increasingly brought to theattention of people, the development of new type of the solar cell which are efficient, clean, lowcost is the development trend of the future. Though the traditional silicon-based solar cells hasbeen applied to some aspects of life, but the manufacturing process will pollute the environment.Although the photoelectric conversion efficiency of copper indium gallium selenide solar cells hasreached twenty percent, the material contains Ga and In two elements which pollute theenvironmental and these two elements in the earth’s content are low, the cost are high, thus itsindustrialization has been very limited. Quaternary chalcogenide semiconductor compound suchas Cu2ZnSnS4, Cu2FeSnS4have the analogous crystal structures to CIGS; Materials of variouselements on the earth are abundant and the environment pollution-free; Light absorptioncoefficient is larger than104/cm; Band gaps between1.0-1.5eV, squarely in the best range of solarabsorption, so quaternary chalcogenide semiconductor compound are increasing getting theattention of people. Recently, the photoelectric conversion efficiency of copper zinc tin sulfur hasreached eleven percent; Copper iron tin sulfur, Copper cobalt tin sulfur and so on are under thedevelopment stage, but the published literature shows that copper iron tin sulfur also has greatapplication value in thin film solar cells. In our paper, we adopt traditional sintering process forthe preparation of copper zinc tin sulfur, and copper zinc tin sulfur is studied and some propertiessuch as the optimum reaction temperature and reaction time were also studied;Besides, we use thecommonly used solvent hot method to synthesis of novel copper nickel tin sulfur, and to determine the optimum reaction factors such as temperature, time, surfactant content by optimizing reactionconditions; what is more, we also studied the formation mechanism of copper nickel tin sulfur.The main job of this paper has two aspects:1. We prepared the copper zinc tin sulfur by sintering method; and by changing thetemperature and time we determined the best reaction temperature and reaction time, which were600°C and10h; under the conditions of the two, we got the largest grain whose crystallizationdegree wae best, but we found that the proportion of each element in the sample were not inconformity with the stoichiometric ratio; it may be that the reaction process was not conducted inan airtight container which resulted in the volatilize of Sn and S.2. We adapted traditional sulfur solvent hot method to synthesize copper nickel tinsulphur and the various properties had been characterized. In the experiment, ethylene glycolsolution, copper sulfate, nickel chloride, stannous chloride were as the metal precursor andthiourea were as the sulfur source as well as polyvinylpyrrolidone as surfactant; In the nextmoment, they were transfered to high pressure reaction kettle; finally we got the flowernanoparticles after230°C response within24hours. We used XRD, SEM, EDS, TEM and UV-Vis instruments to tested the performance of product such as crystal structure, surface morphology,district electron diffraction, light absorption and so on. The results show that we successfullyprepared copper nickel tin nanoparticles, whose composition of each element were in line with thestoichiometric ratio; Moreover, the sample had obvious absorption in the visible light absorptionspectrum and we estimated the energy gap of1.41eV which was just in the best absorption gap ofsolar energy, which showed that the copper nickel tin sulfur had great application value in thefield of solar cell material. To optimize reaction conditions and find out the best reaction way, we had made the research about affection factors respectively which were related to the solventthermal such as temperature, concentration of reaction reagent, the content of surfactant, reactiontime and so on. The experimental results showed that we could obtain pure copper nickel tin sulfurwithout impurity phase only when the reaction temperature was230°C; And we found that wewould get different morphology if the concentration of the reaction reagent and the amount ofPVP; Only when the reaction reagent concentration and the amount of PVP were right, we couldget flower nanoparticles; Finally, in order to explore the formation mechanism of morphology, westudied the influence of reaction time on the morphology of the product and the experimentalresults showed that the development history of flower nanoparticles experienced the process ofnucleation-dissolving-recrystallization; The reaction was originally the reunion of globulargrains; Subsequently, the nanosheet structure were formed by the reunion of globular grains;Finally, some nanosheets were overlapped with each other to form the flower nanoparticles.