2019 Fiscal Year Annual Research Report
Optimization of high-efficiency multi-junction solar cells through homogeneous luminescent coupling effect
| Project/Area Number |
19J13877
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| Research Institution | The University of Tokyo |
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| Research Fellow |
YU JECO BERNICE MAE 東京大学, 工学系研究科, 特別研究員(DC2)
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| Project Period (FY) |
2019-04-25 – 2021-03-31
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| Keywords | concentrator solar / luminescent coupling / light recycling / multijunction solar cell / passivation / luminescence / photonics / photovoltaics |
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| Outline of Annual Research Achievements |
The main question of the role of homogeneous luminescent coupling (LC) effect in high-efficiency multijunction solar cells (MJSCs) was answered. It was found that homogenizing the LC effect may increase the conversion efficiency of III-V MJSCs.
There are three pathways to possibly homogenize and increase current collection in a limiting cell of a III-V MJSC device: one is by growing smaller active area of the top cell, another is by electrical sidewall passivation using thin-film dielectrics, and the other is by photo-passivation of shunt defects in MJSCs using a PQD-amorphous thermoplastic film.
This year, the researcher was able to produce:
3 publications, 2 international conference presentations, and 3 news press releases.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
本年度は、これまでに得られたルミネセンス結合の効果や面内不均一性の結果を基に、電流整合条件を調整して多接合太陽電池の高効率化を図るための具体的な検討を行った。具体的には、InGaP/GaAs/Ge 多接合太陽電池の側壁をatomic layer deposition (ALD) 法で蒸着させたAl2O3 薄膜でパッシベーションした結果、2.5V前後の実際の駆動バイアス電圧条件におけるルミネセンスの面内均一性が、パッシベーション保護をしていないセルと比較して約37.5%改善されることを示した。これにより変換効率も約1.18%の増大が得られた。さらに、多接合太陽電池における電流整合条件を微調整するためのもう一つのアプローチとして、トップセル上にコロイド量子ドット発光体を分散させて、直接GaAsミドルセルへ光を伝搬させる方法を検討し新しい知見が得られた。
多接合太陽電池の新しい評価・解析法を提案し、ルミネセンス結合の面内均一性の改善、及び各サブセル間の電流整合条件の微調整を図ることにより、高効率化が可能であることを明らかにしまとめた博士論文につき、令和2年3月に博士（工学）の学位が授与された。
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| Strategy for Future Research Activity |
The next step targeted next fiscal year is the publication on the results of electrical sidewall passivation and on PQD-amorphous thermoplastic films as solutions to homogenizing the LC effect in III-V MJSCs.
Prior to my transfer to the Department of Urban Engineering with Assoc. Prof. Kumiko Oguma, my upcoming host professor, I have also started my research on the application of III-V concentrator MJSCs on microbial disinfection of water in off-the-grid communities. Fieldwork in Panobolon Island, Guimaras in Western Visayas, Philippines, was conducted from February 12, 2020 to March 10, 2020 to initially assess the MJSC-powered disinfecting device and the available solar insolation on the island. In addition, research partnership with the Provincial Government of Guimaras through Dr. Samuel Gumarin, MD, MPH was sought last March 16, 2020 by polishing the contents of the Memorandum of Understanding with them, targeted to be signed by the middle of the year. This project on the application of high-efficiency MJSCs will be the focus of my 2nd year of JSPS Research Fellow contract.
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