Study On Preparation And Properties Of CuZnSnS And Its Doped Compound Semiconductor Materials

copper-zinc-tin-sulfur(CZTS),As a promising p-type semiconductor material,has an high absorption coefinciency up to 10-4 cm-1 and has abundant raw material reserves,It gradually become a mainstream material in the field of thin-film solar cells.With the deeping research,the preparation process of CZTS thin films is endless.In this thesis,CZTS thin films were prepared by constant potential electrodeposition and pulse electrodeposition in ionic liquids,and Cr-doped CZTS nanocrystalline powders were prepared by solvothermal method.Then Scanning electron microscopy(JSM-6610LV)was used to characterize the surface morphology of the films and powder samples,Energy Dispersive Spectrometer(MCA X-STREAM)was adopted to qualitative and quantitative analysis of the element,X-ray diffraction(*D/MAX-2500/PC)was used to test crystal structure,further qualitative analysis by Raman spectrometer(*/R-500)and X-ray photoelectron spectroscopy(Escalab250XL),UV-Vis-NIR(UV-2550)and Mott-Schottky curve tests the photoelectric properties of the sample.It is planned to prepare a CZTS solar cell absorber layer material with excellent performance through a new process.The main research contents and steps are as follows:1)anhydrous copper chloride(CuCl2),anhydrous stannous chloride(SnCl2),and anhydrous zinc chloride(ZnCl2)are as raw materials,Ionic liquids prepared by choline chloride(C5H14ClNO)and ethylene glycol(C2H6O2)only containing anions and cations are used as solvents,and then step-by-step electrodeposition of copper/tin and zinc under different deposition voltages(-1.0 V,-1.1 V,and-1.2 V),finally sulfated at specific annealing conditions(30min at 300 ?,30min at 500 ?).It was found in the experiment that the stability of the ionic liquid provided a better reaction environment for electrodeposition and that the preliminary annealing step at 300?reduced the loss of tin.The results show that the surface morphology of the sample with a potential of-1.2 V at constant potential electrodeposition is the most uniform and dense,showing a single phase.The Band gap width is closest to the Band gap width of sunlight absorbed by the CZTS film material,and the carrier concentration is also the highest.Obviously,the fast deposition rate and the high deposition potential can easily result concentration polarization during electrodeposition.Therefore,pulse step-by-step electrodeposition process is needed to perform a deeper level of performance exploration.2)Pulse step-by-step electrodeposition belongs to the category of transient measurement techniques.It provides a transition period to restore the semiconductor interface environment to a pre-reaction equilibrium,and then continue to perform the reduction deposition at the initial concentration.The results show that the surface morphology,phase and photoelectric properties of the thin film samples prepared under the deposition voltage of-1.2 V are better than those of the thin film samples deposited under-1.0 V and-1.1 V.compared to the constant potential,step-by-step electrodeposition shows that the surface morphology at the voltage of-1.2 V is significantly more full and more three-dimensional.In the raw material content,the prepared copper-tin film did not show the inhibition to zinc deposition.In terms of photoelectric properties,the band gap value is almost close to the best absorption bandgap Eg(1.5 eV)for the absorption of CZTS to sunlight.Therefore,a CZTS thin film solar cell material having superior performance was prepared by using pulse step-by-step electrodeposition.3)CZTS thin-film semiconductors have become the most promising photovoltaic materials due to their abundant raw materials and excellent photovoltaic performance.These photoelectronic properties can be improved by doping the intermediate state into the energy band,so this thesis attempts to prepare chromium doped CZTS solar cell nanocrystalline powders by solvothermal methods.The anhydrous copper chloride(CuCl2),anhydrous stannous chloride(SnCl2),anhydrous zinc chloride(ZnCl2),anhydrous chromium chloride(CrCl2),thiourea(H2NCSNH2)are as rawmaterials and polyethylene glycol-400(HO(CH2CH2O)H)and ethylene glycol(C2H6O2)were used as solvents,The reaction was carried out at 220 ? in an high pressure reactor for 24 h,then getting sample powder through Centrifugation.After testing,it was found that when the doping amount was 5 mmol/L,the sample surface was spherical and was surrounded by many small balls.The whole was evenly distributed and showed a single phase.In the x-ray diffraction,the intensity of the crystal plane diffraction peak was the highest,and the crystal form was the most well,there also is an angular shift,further analysisin the x-ray photoelectron,chromium has been successfully doped into the zinc,tin lattice,and this chromium doping content than other samples have more excellent photoelectric properties.