Elimination of parasitic effects in floating junction rear surface passivation for solar cells

Abstract

Floating junction (FJ) passivation is a relatively recent passivation scheme which has both experimentally and theoretically demonstrated superior passivation than either oxide or back surface field passivation. In addition, it is suited not only to high efficiency laboratory cells, but also to commercial solar cells. The improvement in surface passivation for commercial cells is an especially critical issue in achieving lower cost solar cells through reducing substrate thickness while simultaneously increasing efficiency. Despite the many advantages of FJ passivation, its applicability has been limited by the apparent inability to translate the excellent modelling results into actual solar cells. The objective of this paper is to present a complete analysis of FJ passivation and to demonstrate a method by which the problems with FJ passivation can be eliminated. Experimental evidence as well as theoretical modelling demonstrates that a solar cell with an optimized rear FJ is insensitive to parasitic effects.