DEVELOPMENT OF TEMPERED-GLASS SUBSTRATES WITH TCO FILMS FOR A-SI SOLAR-CELLS

Tempered-glass substrates with transparent conductive oxide (TCO) film s were developed for a-Si solar cells using an air blasting method. Th e mechanism of thermal deflection arising from the difference of therm al properties between glass and TCO films was investigated using in si tu X-ray diffraction method during heating and cooling processes. It w as found that the deflection was caused by tensile stress induced in t he films at a high temperature above 600 degrees C as well as the diff erence of thermal expansion coefficient between glass and TCO films. I n addition, the stress was found to be closely correlated to the depos ition temperature of the TCO films. Tempered glass with TCO films with small deflection, which passed strength test using a steel ball (227 g, 2.5 m height), was obtained by increasing the deposition temperatur e of the TCO films.