Structural Design And Performance Simulation Of Band Gap Matching Four - Junction GaAs Solar Cells

Currently, multiple-junction tandem solar cells based on GaAs are most competitive, which are the urgent main electric source with good performance and long life-time applied on space. While the traditional 3-j GaAs solar cells have difficulty on improving further. And the novel 4-j solar cells with better efficiency should be put forward by dividing sunlight spectrum. Therefore, in this paper, we would focus on bandgap-matched 4-j GaInP(1.90eV)/GaAs(1.42eV)/InGaAs(1.0eV)//InGaAs(0.7eV). And we have simulated and optimized the solar cell structure by APSYS.(1)The structure of every sub-cell and their performance have been developed thoroughtly by APSYS. And the influence of interface recombination velocity, the thicknesses of base layer and emitter layer, the doping concentrations of base layer and emitter layer, and lifetime of minority carriers on the sub-cell performance have been obtained. The results show: interface recombination velocity, the thicknesses of emitter layer would heavily effect on Jsc, the thicknesses and doping concentration of base layer would obviously impact on Voc,which could be dominant on variety of efficiency; the doping concentration of base layer exhibit clear effect on both Voc and Jsc. And so a knee point should be introduced into the variety of efficiency; lifetime of minority carriers has displayed important role on performance of solar cell,including Voc, Jsc, Eff.(2) According to the basic element of multi-junction solar cell design— the current match, we completed the current match for In0.30Ga0.70As/In0.58Ga0.42 As and Ga0.5In0.5P/GaAs dual-junction solar cells.(3) The optimized structure of InGaP/GaAs/In0.30Ga0.70As/ In0.58Ga0.42 As was revealed, and excellent performance was shown as following, Voc=3540mV,Jsc=20.08 mA/cm2,FF=0.88,Eff=47.8%. And the comparison with the exhibition Voc=3301mV,Jsc=17.33 mA/cm2,FF=0.834,Eff=34.87% of a practical cell with the optimized structure was carried out as well. The results verify the correctness and feasibility of theoretical simulation well.