Non-ideal recombination and transport mechanisms in multiple band gap solar cells

Abstract

The suggestion of the use of multiple band gap solar cells to achieve efficiencies in excess of the homojunction limit has meant that the method for calculating the limiting efficiency has come under scrutiny. In particular, the inclusion of nonradiative transitions and transport apart from drift and diffusion is necessary for a consistent treatment. A method for the inclusion of nonradiative recombination into a three energy level system in a detailed balance framework is presented. Results are presented for the inclusion of an electron-electron Auger process at the central energy level. The results suggest that if the electron escapes to the conduction band edge, the efficiency can be enhanced when away from the optimum band gap arrangement as compared to the cases of no Auger process.