Degradation Analysis of InGaP/GaAs/Ge Triple-junction Solar Cells in High-temperature and High-light- intensity Environments by Luminescence Techniques
| Autor: | Toyota, Hiroyuki, Iwai, Takaaki, Tajima, Michio, Imaizumi, Mitsuru |
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| Jazyk: | japonština |
| Rok vydání: | 2010 |
| Zdroj: | 宇宙エネルギーシンポジウム = Space Energy Symposium. 29 |
| Popis: | 第29回宇宙エネルギーシンポジウム(2010年2月26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス) The twenty-ninth Space Energy Symposium (February 26, 2010, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara) The Institute of Space and Astronautical Science (ISAS) of JAXA is developing two inner-planetary probes: a Venus probe PLANET-C and a Mercury probe MMO. Intense sunlight due to shorter distance to the sun imposes requirements for light-intensity and temperature tolerance on their solar cells. We have been evaluating durability of InGaP/GaAs/Ge triple-junction (3J) solar cells from SHARP Corp. under such environments in two ways: forward current application tests and continuous operation tests.In the forward current application test, we passed current corresponding to two suns of illumination through the solar cells at 200C assuming the PLANET-C condition for 1615 h, which equals to 3230 equivalent solar hours (ESH). This test can be a simple alternative to an actual operation test, though the solar cells operate as LEDs. The maximum power (P(sub max)) of the solar cells declined by 3-6% after the test.In the continuous operation test, we illuminated the solar cells with 9.4 suns of AM 0 light at 230C assuming the MMO condition for 325 h, which equals to 3055 ESH, in a vacuum chamber. This test was a faithful reproduction of the actual environment in contrast to the forward current application test. No significant degradation in P(sub max) was observed after the test.These test results suggested that forward current application causes larger degradation than actual solar cell operation. To examine the difference in detail, we diagnosed the solar cells by photoluminescence (PL) spectroscopy. We applied a selective excitation PL method, which enables separate inspection of each subcell at 4.2 K.PL spectra from InGaP top cells consisted of the band-edge emission at 1.96 eV and 50-80 meV lower energy level. The intensity of these emissions was degraded after the forward current application test, but was not degraded after the continuous operation test. This result agreed with the change in P(sub max)max after the two kinds of degradation tests.PL spectra from GaAs middle cells consisted of the band-edge emission at 1.52 eV, the exciton emission at 1.49 eV, the donor-to-acceptor pair emission at 1.47 eV and its phonon sideband at 1.44 eV. The intensity of the band-edge emission was degraded after the forward current application test, but was not degraded after the continuous operation test in the same manner as the InGaP top cells. This result agreed with the change in P(sub max) after the two kinds of degradation tests. The intensity of the other emissions from GaAs middle cells were degraded after both degradation tests. We will clarify the degradation mechanisms in the future works. 形態: カラー図版あり 形態: CD-ROM1枚 Physical characteristics: Original contains color illustrations Note: One CD-ROM 資料番号: AA0064737003 |
| Databáze: | OpenAIRE |
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