Mechanism investigation on effects of glass composition on Ag/Si contact for crystalline silicon solar cells

Pb–Te–Li oxide glasses have been widely applied in front silver (Ag) paste metallization of crystalline silicon (c-Si) solar cells. In practical application, some other important glass compositions, such Bi 2 O 3 , SiO 2 , ZnO and so on, are often added into Pb–Te–Li oxide glasses to improve the quality of Ag/Si contact. In this paper, the significant effects of these glass compositions on the Ag/Si contact are demonstrated by discussing their influences on the formation of Ag colloids in the interface, the erosion of glass to Si, the glass phase conductivity, and the glass passivation performance at the contact interface. The results show that the addition of Bi 2 O 3 or SiO 2 into the glass may reduce the Ag/Si contact resistivity, because Bi 2 O 3 can promote the formation of Ag colloid in the interface glass layer and increase the interface glass phase conductivity, and SiO 2 can weaken the erosion ability of the glass to keep relatively high dopant concentration in the contacted Si surface. The addition of ZnO into the glass may aggravate the erosion to Si and decrease the glass phase conductivity. It is inferred that increasing Bi 2 O 3 and SiO 2 or reducing ZnO can improve the glass passivation performance at the contact interface. Through the application in Ag paste metallization, the important effects of the glass compositions on the electrical properties of solar cells are shown that Bi 2 O 3 and SiO 2 in the glasses are helpful to increase the open-circuit voltage and short-circuit current, while ZnO is very useful for raising fill factor.