| This thesis presented preparation method of the glass powders which were used in silver paste of crystalline silicon solar cells.For the better properties and lower cost,a series of Pb-Te-Si-B glass powders were prepared and the formula of glass powders was regulated.P was introduced to improve the performance of the glass powders by adding zinc phosphate,and the glass powders were successfully applied to silver paste of crystalline silicon solar cells.The glass powders were prepared by molten method under high temperature first and then quenched in water,and the optimum content of each glass powder component was studied.The content of P was controlled by the amount of zinc phosphate.Besides,milling process of the glass powders was studied and improved.The effect of factors on the particle size was researched through orthogonal experiment,then the glass powders with uniform particle size were prepared by grading ball-milling.Afterwards,the prepared glass powder and the organic vehicle were mixed and printed on silicon wafer.The representative glass powders were selected by studying the surface morphology and the section etching property of the pulp-silicon wafer.Finally,the positive electrode of crystalline silicon solar cells was obtained by mixing the glass powder,silver powder and organic vehicle,followed by screen printing and sintering.In the meanwhile,the optimal sintering process was regulated by the sintering peak temperature and the sintering time according to the properties of the silver film and the battery chip.In summary,the best glass powder was selected and the main results were as follows:(1)The Pb-Te-Si-B glass powders were prepared.It was found that the Tg of the glass powder arose with increasing of the ratio of TiO2,B2O3,ZnO and Li/Na.With the increase of Pb/Te molar ratio,the Tg of glass powder increased rapidly first and then increased slightly.The highest increase rate of Tg was achieved when the ratio of Pb/Te was 1.5.The zinc phosphate can effectively control the performance of glass powder.The increasing of P content can optimize the glass network structure,thereby,the Tg of glass powder was significantly increased.(2)The effect of various milling factors on the milling process was investigated by orthogonal experiment,and the ratio of grinding-ball to material,the match level of grinding ball,the speed of grinding machine,milling time and the ratio of solid to liquid were optimized.Glass powder was grinded by grading ball milling and the optimum conditions were as follows:in first ball milling process,the ratio of grinding-ball to material was 2.5:1,the match level of grinding ball was 2:1:1,the speed of grinding machine was 300r/min,the ratio of solid to liquid was 1:0.8 and milling time was 4h.In second ball milling process,the ratio of grinding-ball to material was 3.5:1,the match level of grinding ball was 1:1:1,the speed of grinding machine was 400r/min,the ratio of solid to liquid was 1:0.8 and milling time was 3h.The obtained glass powder came up to the requirements of the solar cell positive silver paste.(3)The selected glass powders with silver powders and organic vehicle were mixed to obtain positive silver pastes.Then the effect of sintering peak temperature and sintering time on the properties of silver film and battery were studied.The optimum sintering peak temperature and sintering time was 970℃ and 130s,respectively.For the Pb-Te-Si-B glass powder,when P content was 4.5%,the series resistance of polycrystalline silicon solar cell prepared was 0.011 Ω,and the maximum photoelectric conversion efficiency was 18.56%.The formula of this glass powder was PbO-45.17%,TeO2-21.53%,SiO2-8.2%,B2O3-7.8%,Li2O-0.4%,Na2O-0.2%,P205-4.5%,ZnO-8.3%Ti02-2%,V2O5-1.9%. |
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