Fusion formable sodium free glass

摘要

A compositional range of fusion-formable, high strain point sodium free, silicate, aluminosilicate and boroaluminosilicate glasses are described herein. The glasses can be used as substrates for photovoltaic devices, for example, thin film photovoltaic devices such as CIGS photovoltaic devices. These glasses can be characterized as having strain points≧540° C., thermal expansion coefficient of from 6.5 to 10.5 ppm/° C., as well as liquidus viscosities in excess of 50,000 poise. As such they are ideally suited for being formed into sheet by the fusion process.

主权项

1. A glass comprising, in weight percent:
45 to 75 percent SiO2; 3 to 15 percent Al2O3; 3 to 20 percent B2O3 21 to 25 percent K2O; 0 to less than 6 percent MgO; 0 to 10 percent CaO; 0 to less than 5 percent SrO; 0 to 3.32 percent BaO; and greater than 0 to 1 percent SnO2, wherein the glass is substantially free of Na2O and wherein the glass is fusion formable and has a strain point of 540° C. or greater, a coefficient of thermal expansion of 50×10−7/° C. or greater, T200 less than 1630° C., and having a liquidus viscosity of 150,000 poise or greater.