Procedures for evaluating multijunction concentrators

Abstract

Procedures at NREL and Fraunhofer ISE for evaluating multijunction cells are detailed with a triple-junction GaInP/GaAs/Ge concentrator cell designed and grown at Spectrolab and processed at NREL, and a tandem Fraunhofer ISE Ga/sub 0.35/In/sub 0.85/P/Ga/sub 0.83/In/sub 0.17/As cell as examples. The one-sun efficiency and I/sub sc/ for the triple-junction device measured at Fraunhofer ISE and NREL agreed within 0.2%, well below the /spl plusmn/6% uncertainty estimated by NREL. The procedures for determining the one-sun characteristics involve determining the quantum efficiency and using it for spectral correction during the I-V characterization. The characteristics under concentration are evaluated with a flash simulator.