Electrodeposition Preparation Of Silver Indium Sulfur Photoelectric Thin Film And Its Properties

Solar energy has endless advantages,and solar thin film cells are one of the ways to use solar energy effectively.The important component of solar thin film cells is their absorber layer,which draws the attention of mankind.In recent years,?-?-VI semiconductor compound materials have been rapidly developed in the field of optoelectronics due to their high absorption coefficient and green environmental protection.AgInS₂,a ternary I-III-VI semiconductor compound,also has the advantages of high light absorption coefficient and environmental friendliness,so it can be used as an absorber layer material.The doping of elements is one of the ways to improve the properties of materials.In this thesis,based on the first nature principle,the geometric structure and optical properties of AgInS₂ doped with Al and Ga elements were investigated using Materials Studio software with the intention of improving the properties of the material;in this thesis,AgInS₂ thin films were prepared by electrodeposition in different solvent systems,and their physical and morphological analysis was carried out using XRD,SEM and EDS,and The performance tests were carried out on their optoelectronic properties.(1)In this thesis,the doping simulations of AgInS₂ crystal structure were calculated by using Materials Studio software,and the AgInS₂ doped with Al and Ga in chalcopyrite structure,the cell volume becomes smaller after doping with Al and Ga,and the cell volume decreases with the increase of doping amount;after doping with Al and Ga,the energy bands of AgIn_xAl_1-xS₂,AgIn_xGa_1-xS₂(x=0.25,0.5,0.75)are larger than those of AgInS₂,and the forbidden band width is found to increase with the increase of Ga and Al doping.Therefore,the forbidden band width of AgIn_1-xGa_xS₂ can be adjusted between the forbidden band width ranges of AgInS₂ and Ag GaS₂,and the forbidden band width of AgIn_1-xAl_xS₂,and by analyzing the density of distributed states,it was found that Ga doping had an effect on the conduction band minimum,leading to an upward shift of the conduction band minimum,which in turn influenced the band width,while Al doping mainly affected the In-s bond energy,which in turn influenced the band width;the absorption of AgInS₂ reached its peak when the wavelength was 150 nm,and after doping with Al and Ga,the peak increase became larger,and with the increase of doping AgInS₂has good absorption in the UV range,and after doping with Al and Ga,it also maintains good absorption of UV light.(2)We investigated the effects of different electrodeposition conditions and composition of electrodeposition solution on the phase and morphology of AgInS₂ films in aqueous solution system,and found that the best electrodeposition solution composition was 5 mmol/L Ag NO₃,5 mmol/L In(NO₃)₃,100 mmol/L Na₂S₂O₃·H₂O,2 mmol/L Na₃C₆H₅O₇,20 mmol/L Na₂SO₄;the best electrodeposition conditions were at-1.0V for 30 min at a constant potential,a controlled deposition temperature of 40°C,a solution p H of 4,and a heat treatment at 400°C for 1 h.At this time,the film had the best crystallinity and a uniform and dense surface,and the conductivity was 1.142×10^-2 s/cm.(3)In the mixed solution system,we chose water-ethanol as the solvent,mainly because it has the widest electrochemical window,the best conductivity and better electrochemical stability;we studied the effect of ethanol on the electrochemical behaviour of the mono-and multi-solution systems and found that ethanol promoted the reduction of Ag⁺and S^2-to a certain extent,resulting in a negative shift of the deposition potential,while the effect on In³⁺was not very obvious;The effects of electrodeposition conditions and composition of the electrodeposition solution on the phase and morphology of AgInS₂ films were investigated,and the optimal electrodeposition solution composition was the same as that of the aqueous system.The best composition of the electrodeposition solution was the same as that of the aqueous system,and the films were deposited at a constant potential of-1.0 V for 30 min,the deposition temperature was maintained at 30°C,and the films were heat-treated at 200°C for 24 h after completion of electrodeposition.