Effect of sawing damage on flexibility of crystalline silicon wafers for thin flexible silicon solar cells

Abstract

The cost of solar cell production can be reduced by wafer thinning. A thinner wafer provides flexibility, and crystalline silicon solar cells are promising as flexible solar cells due to their flexibility. However, as wafers become thinner, production yield decreases due to wafer breakage caused by sawing damage; thus, to further reduce wafer thickness, it is necessary to suppress sawing damage. We investigated the flexibility of wafers under various slice conditions by conducting biaxial bending tests and clarified the dominant factor causing sawing damage to further reduce the wafer thickness for crystalline silicon solar cells. The results of damage observation by scanning electron microscopy and evaluation of the crystal structure by Raman spectroscopy confirm that the damage structure changes significantly depending on wire specifications. The results from the biaxial bending tests indicate that the three-dimensional flexibility of a wafer is determined by wire specifications.