Characteristics of Pb-based glass frit prepared by spray pyrolysis as the inorganic binder of silver electrode for Si solar cells

Pb-based glass frit, which acts as an inorganic binder of a silver electrode in Si solar cells, is directly prepared by spray pyrolysis. The optimum temperature for the preparation of a spherical-shaped glass frit with narrow size distribution was 1400 °C. The mean size and geometric standard deviation of the glass frit were 0.86 μm and 1.63, respectively. The glass transition temperature (T_g) of the glass frit prepared by spray pyrolysis was 487.2 °C. Melting of silver powders occurred at a firing temperature of 500 °C. However, a number of pores inside silver conducting films fired at a temperature of 500 °C are observed in the scanning electron microscopy (SEM) images. Silver conducting films fired at temperatures of 700 °C and 800 °C had dense structures with a small number of internal pores. The silver conducting film fired at a temperature of 800 °C had a large grain size. Glass materials were segregated between micron-sized silver grains at high firing temperatures of 700 °C and 800 °C. The specific resistance of silver conducting films made from glass frit prepared at a temperature of 1400 °C decreased from 4.5 μΩ cm to 2.6 μΩ cm.