Considerations on the Solar Cell

Abstract

The collection efficiency in solar cells is trealed by a new method in which all the effects of the solar spectrum and the absorption curve are contained in a single funetion readily obtained by numerical integration. The method is illustrated by a detailed study of the effects of surface recombination, body recombination and junction depth in silicon cells. The method is also generalized to include built-in electric fields, and calc Illations are given for silicon. Sufficiently strong fields 10 improve the collection efficiency markedly can be produced in some compollnd semiconductors from a gradient in the energy gap. A disclLssion is given of the dependence of the collection efficiency on the absorption curve of the semiconductor. It is shown that silicon has a very favorable absorption curve in camparison with GaAs or InP. Finally, a treatment is given of the minority carrier collection in a two-Junction cell, and calculations arc presented for silicon. It is concluded that this structure may be important for cells with high energy gaps and short lifetimes.