Preparation And Characterization Of Copper-iron-selenium Optoelectronic Materials

Thin-film solar cells have attracted the attention of new energy researchers due to their high efficiency,low production cost,and stable performance.As a photoelectric material,CuFeSe₂ has the advantages of high light absorption coefficient,strong conversion rate,abundant raw materials and cheapness.It is a very narrow band gap semiconductor and can be used as the material of the main structure absorption layer of thin-film solar cells;FeSe and FeSe₂ have low cost,band The advantages of good gap width,good thermal stability,etc.,have high potential application value.The energy band,structure and optical properties of CuFeSe₂ system were analyzed by MS software;FeSe and FeSe₂ nano powders were prepared by hydrothermal method,and CuFeSe₂ thin films were prepared by spin coating co reduction method.The products were characterized by XRD,SEM,EDS and four probe.The main contents are as follows:(1)Using the CASTEP program in the Materials studio software,based on the optimization of the geometric structure,calculate the energy bands and bands of CuFeSe₂ and CuFe(Se_1-xS_x)₂ whose S atom concentration is 1/4,1/2,and 3/4,respectively.Optical properties.After optimizing the doping of S atoms in CuFeSe₂,it is found that the forbidden band width and cell volume of CuFe(Se_1-xS_x)₂ are related to the concentration of doped S atoms.As the concentration of doped S atoms increases,the volume of the cell gradually increases.Decrease,the forbidden band width gradually increases,but its range is within the forbidden band width of CuFeSe₂and CuFeS₂.(2)The CuFeSe₂ film was prepared by spin-coating co-reduction method.The study found that the CuFeSe₂ film can be prepared when the reaction temperature is 160??220? and the reaction time is 2h-40h.The CuFeSe₂ film prepared when the reaction temperature is180? and the reaction time is 20h has the best crystallization effect.The morphology of the material was studied by scanning electron microscopy,and it was found that the crystal grains were mostly composed of elliptical and block shapes,with a length of about 0.5?m-2?m.The types and contents of elements in the film were analyzed by an energy spectrometer,and they were found to contain Cu,Fe,and Se are also in line with the element ratio of the compound;the conductivity and resistivity of the sample are obtained by a four-probe tester.It is found that when the reaction time changes with the reaction temperature,the conductivity and resistivity of the sample do not change.obvious.The effect of different solvents on the phase formation of the prepared film was studied,and it was found that CuFeSe₂ film was successfully prepared using absolute ethanol as the solvent,but from the morphology,it was found that agglomeration was common,the film had large pores and poor continuity;hydrochloric acid was used as the solvent to prepare the CuFeSe₂film.The CuFeSe₂ film has good morphology,uniform film coating,good compactness,good phase formation,impurity NaCl is generated,and deionized water infiltration can remove impurities,but if it is infiltrated for too long,it will destroy the film morphology.(3)The FeSe powder was prepared by hydrothermal method.The influence of different reaction time and temperature on the phase of FeSe prepared is studied.When the temperature changes,the higher the temperature,the better the crystallinity of the target product FeSe crystal;whether it is a short-term reaction or a long-term reaction,The effect of changing temperature on the removal of impurity Se crystals is not obvious;as the reaction time increases at different reaction temperatures,the diffraction peaks of the target product gradually increase,and impurity Se crystals and impurity FeSe₂ crystals gradually disappear;the morphology of the material is studied by SEM analysis Structure,it is found that the crystal grains are mostly elliptical and the length is about 1-3?m;the powders prepared by EDS analysis contain Feand Se elements;finally,the FeSe powder has the best crystallization effect when the reaction temperature is 220? for 20h.(4)The FeSe₂ powder was prepared by hydrothermal method.The FeSe₂ powder with chalcopyrite structure was successfully prepared using hydrochloric acid as the solvent.Mainly analyze the influence of different heat treatment conditions on the morphology and phase of the product.From a microscopic point of view,FeSe₂ crystals are round-shaped particles with a diameter of 1?3?m;the effect of different heat treatment conditions on the phase of the prepared FeSe₂ is studied;it is found that changing the temperature and time has the effect of removing impurity Se crystals and impurity FeSe crystals Not obvious;but the crystallinity of the target product is affected by the reaction time and temperature.When the reaction time is very high and gradually reaches 40h,the target product FeSe₂ crystals will gradually disappear;the powders prepared by EDS analysis all contain Feand Se elements;The results show that the FeSe₂ powder has the best crystallization effect when the reaction temperature is 180?and the time is 10h.