Analysis and control of defects in wide-gap thin-film photovoltaic devices

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05282
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Ishizuka Shogo 国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 研究グループ長 (60415643)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 化合物薄膜 / 太陽電池 / エネルギー変換 / 薄膜 / 半導体

Outline of Final Research Achievements

For conventional photovoltaic solar cells, R&D on a single junction, based on crystalline Si, which can absorb the sunlight in a relatively wide wavelength range, have been dominant for practical applications. For these years, however, multi-junction solar cell technologies are expected to demonstrate high photovoltaic efficiencies beyond the SQ limit, and are attracting attention. To realize highly efficient and cost-effective multi-junction solar cells, R&D of low-cost and high-efficiency top cell materials which have a wider band-gap energy (Eg) than that of conventional Si (Eg~1.1 eV) is necessary. This subject focuses on chalcopyrite CuGaSe2 (Eg~1.7 eV) as a promising top cell material for practical applications for this purpose. The control of material properties of thin-films and improvement of solar energy conversion device performance are investigated.

Free Research Field

応用物理、半導体工学、太陽電池、薄膜、エネルギー変換

Academic Significance and Societal Importance of the Research Achievements

Cu(In,Ga)Se2（CIGS）太陽電池に代表されるカルコパイライト系化合物薄膜太陽電池においては、その組成比等の制御により禁制帯幅を広範囲で制御が可能である。しかし理論予測に反し、禁制帯幅の増加に伴い開放電圧の伸びの鈍化や曲線因子の低下が見られ、広禁制帯幅CIGS系材料の高品質化は長年の課題であった。本研究では、広禁制帯幅CIGS系材料の一つである三元系CuGaSe2に着目し、その欠陥制御とデバイス高性能化に取り組んだ。結果、第三者機関測定値としてCuGaSe2太陽電池の世界最高効率を実現し、広禁制帯幅CIGS系材料が有望なタンデム型太陽電池材料と成り得ることを実証した。