InGaAsP/InGaAs tandem cells for a solar cell configuration with more than three junctions

Currently, triple‐junction solar cells realized from III–V semiconductor compounds hold the solar energy conversion efficiency world record. To improve the efficiency significantly, it is necessary to increase the number of junctions and to involve a sub‐cell with an absorber layer in the band gap range of 1 eV. For the realization of a stacked four‐junction device with optimised band gaps, we have grown InGaAsP/InGaAs tandem cells lattice matched to InP substrates, and investigated properties of the absorber bulk material. Time‐resolved photoluminescence of the low band gap In0.53Ga0.47As absorber embedded between InP barriers was measured. The InGaAs/GaAsSb tunnel diode structure used in the tandem has been processed into a separate device and I –V curves were measured. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) To realize a stacked four junction device with optimised band gaps, InGaAsP/InGaAs tandem cells lattice matched to InP substrates were grown. Time‐resolved photoluminescence of the low band gap In0.53Ga0.47As absorber embedded between InP barriers is presented. The InGaAs/GaAsSb tunnel diode structure used in the tandem has been processed into a separate device and its I –V curves are discussed.