Back contacted emitter GaAs solar cells

A device structure to improve the performance of GaAs concentrator solar cells is described, and the first experimental results are reported. The reason for such an improvement is a drastic reduction of the shadowing and series resistance losses based on the possibility of back contacting the emitter region of the solar cell. This innovative structure offers the possibility of surpassing the 28% efficiency (100 mW AM1.5 direct spectrum), with present GaAs technology. Furthermore, it allows the shifting of the optimum concentration ratio to very high levels (in the range of 1000 suns). The experimental results obtained with devices of this type, which have a simplified structure and are fabricated by liquid phase epitaxy (LPE), demonstrate the feasibility and correct operation of the proposed back contact of the emitter of the cells