Photolumineseenee measurements are carried out to investigate the injection-enhanced annealing behavior of electron radiation-induced defects in a GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells which a...Photolumineseenee measurements are carried out to investigate the injection-enhanced annealing behavior of electron radiation-induced defects in a GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells which are irradiated by 1.8 MeV with a fluence of i ~ 1015 cm-2. Minority-carrier injection under forward bias is observed to enhance the defect annealing in the GaAs middle cell, and the removal rate of the defect is determined with photoluminescenee radiative efficiency recovery. Furthermore, the injection-enhanced defect removal rates obey a simple Arrhenius law. Therefore, the annealing activation energy is acquired and is equal to 0.58eV. Finally, in comparison of the annealing activation energies, the E5 defect is identified as a primary non-radiative recombination center.展开更多
Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons ...Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons with fluences ranging up to 3 × 10^15, 1 × 10^15 and 3 × 10^14 cm^-2, respectively. The degradation rates of PL intensity increase with the electron fluence and energy. Furthermore, the damage coefficient of minority carrier diffusion length is estimated by the PL radiative efficiency. The damage coefficient increases with the electron energy. The relation of damage coefficient to electron energy is discussed with the non-ionizing energy loss（NIEL）, which shows a quadratic dependence between damage coefficient and NIEL.展开更多
In a conventional flat plate solar cell under direct sunlight,light is received from the solar disk,but is re-emitted isotropically.This isotropic emission corresponds to a significant entropy increase in the solar ce...In a conventional flat plate solar cell under direct sunlight,light is received from the solar disk,but is re-emitted isotropically.This isotropic emission corresponds to a significant entropy increase in the solar cell,with a corresponding drop in efficiency.Here,using a detailed balance model,we show that limiting the emission angle of a high-quality GaAs solar cell is a feasible route to achieving power conversion efficiencies above 38%with a single junction.The highest efficiencies are predicted for a thin,light trapping cell with an ideal back reflector,though the scheme is robust to a non-ideal back reflector.Comparison with a conventional planar cell geometry illustrates that limiting emission angle in a light trapping geometry not only allows for much thinner cells,but also for significantly higher overall efficiencies with an excellent rear reflector.Finally,we present ray-tracing and detailed balance analysis of two angular coupler designs,show that significant efficiency improvements are possible with these couplers,and demonstrate initial fabrication of one coupler design.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10675023,11075018 and 11375028the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20120003110011
文摘Photolumineseenee measurements are carried out to investigate the injection-enhanced annealing behavior of electron radiation-induced defects in a GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells which are irradiated by 1.8 MeV with a fluence of i ~ 1015 cm-2. Minority-carrier injection under forward bias is observed to enhance the defect annealing in the GaAs middle cell, and the removal rate of the defect is determined with photoluminescenee radiative efficiency recovery. Furthermore, the injection-enhanced defect removal rates obey a simple Arrhenius law. Therefore, the annealing activation energy is acquired and is equal to 0.58eV. Finally, in comparison of the annealing activation energies, the E5 defect is identified as a primary non-radiative recombination center.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11675020,11375028,11075018 and 10675023
文摘Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons with fluences ranging up to 3 × 10^15, 1 × 10^15 and 3 × 10^14 cm^-2, respectively. The degradation rates of PL intensity increase with the electron fluence and energy. Furthermore, the damage coefficient of minority carrier diffusion length is estimated by the PL radiative efficiency. The damage coefficient increases with the electron energy. The relation of damage coefficient to electron energy is discussed with the non-ionizing energy loss（NIEL）, which shows a quadratic dependence between damage coefficient and NIEL.
基金Thanks to D Callahan,M Sheldon and J van de Groep for insightful discussions and advice on the manuscript.The authors also found advice from O Miller on handling non-radiative recombination,R Briggs on mode structure calculations,J Zipkin on numerical methods and C Eisler on internal fluorescence yield derivations extremely helpful.The authors are grateful for technical assistance from G Vollenbroek.The Caltech researchers are supported by the‘Light-Material Interactions in Energy Conversion’Energy Frontier Research Center funded by the US Department of Energy,Office of Science,Office of Basic Energy Sciences under grant DE-SC0001293(EK and HA).EK also acknowledges the support of the Resnick Sustainability Institute.Researchers of the Center for Nanophotonics at AMOLF are supported by the research program of FOM which is financially supported by NWO and by the European Research Council.
文摘In a conventional flat plate solar cell under direct sunlight,light is received from the solar disk,but is re-emitted isotropically.This isotropic emission corresponds to a significant entropy increase in the solar cell,with a corresponding drop in efficiency.Here,using a detailed balance model,we show that limiting the emission angle of a high-quality GaAs solar cell is a feasible route to achieving power conversion efficiencies above 38%with a single junction.The highest efficiencies are predicted for a thin,light trapping cell with an ideal back reflector,though the scheme is robust to a non-ideal back reflector.Comparison with a conventional planar cell geometry illustrates that limiting emission angle in a light trapping geometry not only allows for much thinner cells,but also for significantly higher overall efficiencies with an excellent rear reflector.Finally,we present ray-tracing and detailed balance analysis of two angular coupler designs,show that significant efficiency improvements are possible with these couplers,and demonstrate initial fabrication of one coupler design.
