Mirrored strain-balanced quantum well concentrator cells in the radiative limit

Abstract

Strain-balanced Quantum Well Solar Cells (SB- QWSCs) are radiatively dominated at concentrator current levels. Incorporating back surface mirrors on the back of the doped substrate leads to a reduction in this radiative recombination current while the non-radiative dark current at lower bias remains unchanged. This work extends a previous model of radiative dark currents to cells where the substrate is not a perfectly absorbing sink for emitted luminescence by including multiple passes of photons emitted by radiative recombination. The luminescence in such mirrored structures is reduced and the radiative dark current lower. The structure is suited to concentrator applications because it corresponds to the high efficiency limit where losses due to light re-emission are limited to the solid angle for absorption of solar radiation.