Preparation And Research Of Graphene Modified Lead-free Glass Frit Used As Front Electrode Of Crystalline Silicon Solar Cells

At present,energy has become an essential material condition for the survival and development of human beings.However,the use of traditional energy is limited,crystalline silicon solar cells have attracted remarkable attention in recent years as a promising renewable clean energy source because of their high photoelectric conversion efficiency and dependable mass production.In this paper,the preparation of lead-free glass frit and graphene doped lead-free glass frit in front silver paste were studied,and the effects on the electrical properties of solar cell were summarized by a series of test methods.Three kinds of Bi-Te-B-Si-P-O lead-free glass frits with different mass fraction ratios of B₂O₃/SiO₂?10/4,6/8,and 2/12?were prepared by melt cooling route.The smallest particle size distribution(D₉₀=3.40m)was achieved by smashing in high speed multifunctional pulverizer for 75 min.Glass frits were characterized by means of X-ray powder diffractometer?XRD?,infrared spectrometer?FT-IR?and thermal analyser?TG/DSC?.We investigated that the effect of those B₂O₃/SiO₂ ratios on the transition temperature?T_g?of glass frits,and their T_g were 311 ?,347 ?,and 366 ?,respectively.The T_g of the glass frit is one of the most significant properties that determine the glass behavior.The purchased crystal silver powder,prepared glass frit and organic carrier were mixed to prepare the silver paste for solar cell by three-roll grinding machine.Then,the influence of T_g on cross-sectional microstructures of the front-silver electrodes,the Ag crystallites distribution on Si substrate,and electrical performance of solar cells were studied.The fabricated solar cell showed the lowest series resistance?0.0017??and the highest photoelectric conversion efficiency?18.260%?based on the glass frit T_g of 347 ?.Graphene and graphene doped glass frit were successfully synthesized by using graphene oxide as precursor through hydrothermal reduction method.Graphene was homogeneously doped into glass powder when diethylene glycol was used as reducing agents compared with other reducing agents.The influence of mass ratio of GO and lead-free glass powder on the surface morphology and cross section morphology of positive silver electrode were analyzed and discussed.The effect on the welding tension of silver electrode and silicon substrate and electrical properties were also discussed.The results showed that when the mass ratio of GO to lead-free glass was 0.05,the surface of the silver grid line was the most compact and smooth,the welding tension between the silver grid line and the silicon substrate was the largest,and the electrical properties were also optimal.It could obviously reduce the series resistance and improve the photoelectric conversion efficiency of the solar cell.