Analysis for current-voltage characteristics of the InGaAs/GaAsP super-lattice solar cells under optical concentration

Abstract

Novel band engineering material of a super-lattice (SL) consists of strain-balanced InGaAs and GaAsP was applied to GaAs p-i-n single junction solar cells. The SL solar cell sample with 60 periods of 5.4-nm-thick In0.13Ga0.87As well and 3.1-nm-thick GaAs0.75P0.25 barrier showed extended quantum efficiency cutoff from 870 nm to 930 nm, resulted in substantial increment of short circuit current density ΔzlJSC=2.1 mA/cm. Comparing current-voltage (I-V) characteristics under the different illumination condition from 1SUN to 200 SUN for the bulk GaAs cell and the SL cell, the fraction of ΔzlJSC was constant in this range. And the increasing dependency of open circuit voltage (VOC) of SL cell on concentration ratio showed steeper tendency than the bulk GaAs cell. Finally the SL cell achieved larger conversion efficiency (η) than the bulk GaAs p-i-n junction solar cell under >100 SUN.