GaInAsP solar cells with the ideal band gap for terrestrial concentrator applications

Computer modeling studies of single-junction solar cells have been used to determine the ideal band gap for operation under concentration. Results of the modeling show that the presence of absorption bands in the direct spectrum have the effect of “pinning” the optimum band gap for a wide range of operating conditions at a value of 1.14 eV. The model predicts that practical efficiencies exceeding 30% are possible at high concentration ratios for devices with the ideal band gap. This paper describes the authors´ initial attempts to fabricate concentrator solar cells with a band gap of 1.14 eV from the quaternary alloy GaInAsP lattice matched to InP. An efficiency value of 27.5% at 171 Suns is reported for this device and areas for future improvement are outlined