Characterizations of Radiation Damage in Multijunction Solar Cells Focused on Subcell Internal Luminescence Quantum Yields via Absolute Electroluminescence Measurements

• Published in: IEEE journal of photovoltaics Vol. 6; no. 3; pp. 777 - 782
• Main Authors: Lin Zhu, Yoshita, Masahiro, Shaoqiang Chen, Nakamura, Tetsuya, Mochizuki, Toshimitsu, Changsu Kim, Imaizumi, Mitsuru, Kanemitsu, Yoshihiko, Akiyama, Hidefumi
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.05.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Damage; Degradation; Electroluminescence; Electroluminescence (EL); Energy measurement; Fluctuation; Gallium arsenide; III-V semiconductor materials; Luminescence; Photonic band gap; Photovoltaic cells; Protons; Radiation damage; Radiation effects; Solar cells; space photovoltaics (PV); Voltage measurement; photovoltaic cells; Electroluminescence (EL); III–V semiconductor materials; luminescence; radiation effects; space photovoltaics (PV)
• ISSN: 2156-3381; 2156-3403
• DOI: 10.1109/JPHOTOV.2016.2540247

Via absolute electroluminescence measurements, we characterized degradations of internal luminescence quantum yield or internal radiative efficiency (η inti ) in respective subcells in GaInP/GaAs/Ge triple-junction and GaInP/GaAs double-junction solar cells after irradiations of protons and electrons with different energy and fluence (φ). Compared with typical open-circuitvoltage characterizations, η inti turned out to be a sensitive, high-dynamic-range, quantitative, and fair indicator of radiation damage, since it purely represents material-quality change due to radiation damage, independently from small differences in bandgap energy due to alloy composition fluctuations and in other cell structures. A detailed fluence-dependence study has shown that the data of η inti versus φ in moderate and high φ regions are very similar and almost independent of subcell materials, while the difference in beginning-of-life qualities of GaInP and GaAs materials causes dominant difference in subcell sensitivity to the low-radiation damages.