Novel Bandgap grading technique for enhancing the limiting efficiency of solar cells

The efficiency of solar cells is limited by radiative and/or Auger recombination losses. Radiative recombination can be reduced by limiting the escape angle of the reemitted rays. Auger recombination can be reduced by limiting the cell's thickness. A novel technique for reducing the Auger recombination limit is proposed in this work. We show that bandgap grading can be effectively utilized to suppress the Auger recombination limit. The optimum bandgap grading profile that maximizes the limiting efficiency for an idealized, one dimensional solar cell is hence calculated under AM0 irradiation conditions.