Fusion Formable Silica and Sodium Containing Glasses

摘要

Sodium containing aluminosilicate and boroaluminosilicate glasses are described herein. The glasses can be used as substrates or superstrates for photovoltaic devices, for example, thin film photovoltaic devices such as CIGS photovoltaic devices. These glasses can be characterized as having strain points ≧535° C., for example, ≧570° C., thermal expansion coefficients of from 8 to 9 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 consisting essentially of in weight percent:
50 to 72 percent SiO2; greater than 15 to 25% percent Al2O3; 0 to 10 percent B2O3; 10 to 25 percent total M2O; and greater than 0 to 25 percent total RO; wherein M is an alkali metal selected from Na, K, Li, Rb, and Cs, wherein the glass comprises at least 9 weight percent Na2O, wherein R is an alkaline earth metal selected from Mg, Ca, Ba, and Sr, wherein the glass has a strain point of 535° C. or greater, a coefficient of thermal expansion of 50×10−7 or greater, and a liquidus viscosity of 130,000 poise or greater.