An analytical model for high-low-emitter (HLE) solar cells in concentrated sunlight

A current-voltage characteristic is derived for the high-low emitter (HLE) solar cell in concentrated sunlight. For high-level injection, the ambipolar approach is used to yield the complete information of the low emitter concentration region, including the ohmic drop, the Dember voltage, the minority carrier current density, the minority-carrier distribution and the electric field distribution. High doping effects including Auger recombination and bandgap narrowing are considered. The dependences of short-circuit current, open-circuit voltage, fill factor and conversion efficiency on the variations of the geometrical dimensions and material parameters are discussed in detail for silicon single crystal materials. It is shown that the maximum conversion efficiency of 22% at 100 suns AMO can be obtained for silicon high-low emitter solar cell.