Effect of Pb-Te-Si-O glasses on Ag thick-film contact in crystalline silicon solar cells

Abstract In the paper, the influences of Pb–Te–O (PTO) glasses with different Pb/Te ratios on silver screen-printed contact formation in crystalline silicon solar cells were investigated. Thermal properties of PTO glasses such as crystallization behavior, liquidus temperature and viscosity–temperature features are determined by Pb/Te ratio. Glass etching reaction, Ag dissolution–precipitation process and all key processes of Ag thick-film contact to crystalline silicon solar cells, are closely related to glass chemistry and Pb/Te ratio of PTO glasses. The dissolution process of Ag in PTO glasses with different Pb/Te ratio was studied. XPS measurement shows that Ag + is the dominant form of silver dissolved in PTO glass melts. TG and XRD results reveal that the formation of a new B-rich liquid glassy-phase, induced by the crystallization of glass, accelerates the dissolution of Ag at lower temperature. Glass with higher Pb/Te ratio has a weaker glass etching reaction ability and is expected to have a high high-temperature viscosity, resulting in higher Ag-precipitate density in the glassy-phase. The observed microstructures, I – V electrical performance and contact resistance maps lead to a better understanding of the relationship between glass properties and contact resistance.

[1]  Liang Liang,et al.  Nano-Ag colloids assisted tunneling mechanism for current conduction in front contact of crystalline Si solar cells , 2009, 2009 34th IEEE Photovoltaic Specialists Conference (PVSC).

[2]  S. Sankaranarayanan,et al.  Application of optical basicity to viscosity of high alumina blast furnace slags , 2010 .

[3]  Ajeet Rohatgi,et al.  Effect of glass frit chemistry on the physical and electrical properties of thick-film Ag contacts for silicon solar cells , 2006 .

[4]  J. Huh,et al.  Mechanism for the formation of Ag crystallites in the Ag thick-film contacts of crystalline Si solar cells , 2009 .

[5]  Ajeet Rohatgi,et al.  Investigation of the Mechanism Resulting in low Resistance Ag Thick-Film Contact to Si Solar Cells in the Context of Emitter Doping Density and Contact Firing for Current-Generation Ag Paste , 2014, IEEE Journal of Photovoltaics.

[6]  L. Liang,et al.  Electron microscopy study of front-side Ag contact in crystalline Si solar cells , 2009 .

[7]  Christophe Ballif,et al.  Silver thick-film contacts on highly doped n-type silicon emitters: Structural and electronic properties of the interface , 2003 .

[8]  Hyunjin Park,et al.  Role of PbO-based glass frit in Ag thick-film contact formation for crystalline Si solar cells , 2009 .

[9]  M. Ingram,et al.  An interpretation of glass chemistry in terms of the optical basicity concept , 1976 .

[10]  M. Ingram,et al.  Establishment of an optical scale for Lewis basicity in inorganic oxyacids, molten salts, and glasses , 1971 .

[11]  Song-Yeu Tsai,et al.  Investigation of Ag-bulk/glassy-phase/Si heterostructures of printed Ag contacts on crystalline Si solar cells , 2008 .

[12]  S. Takeda,et al.  Coloration due to colloidal Ag particles formed in float glass , 2000 .

[13]  F. Huster,et al.  Physical understanding of printed thick-film front contacts of crystalline Si solar cells—Review of existing models and recent developments , 2006 .