Electrons and holes in solar cells with partial rear contacts

Abstract

When the metal contact of a silicon solar cell is restricted to a fraction of the rear surface, the flow of electrons and holes towards that contact is constricted, which is beneficial for minority charge carriers but detrimental for majority carriers. It is possible to describe their 2D/3D transport and determine their concentration in the vertical and transversal dimensions of the solar cell by separately studying the central region near the contact and the peripheral region surrounding it. A virtue of such geometric approach is that it establishes a link between analytical models and computer simulations, providing both physical insight and sufficient accuracy to optimise partial rear contact devices. In this paper, we extend a previous version of the geometric model to solar cells having a full-area, locally contacted dopant diffusion on the rear surface. The case for n-type versus p-type wafers is considered, point contacts are compared with line contacts, including the impact of the metal/semiconductor resistance and bulk recombination is evaluated.