The improvement of efficiency and durability in organic solar cells by nanometer-size metal particles

• Project/Area Number: 18K04292
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: Ritsumeikan University
• Principal Investigator: HARAFUJI Kenji 立命館大学, 理工学部, 教授 (60442472)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 有機太陽電池 / 電力変換効率 / 光照射耐久性 / 薄膜金属層 / 加熱処理 / 金ナノ粒子 / プラズモン効果 / 電力変化効率 / 貴金属微粒子 / 薄膜金層 / 加熱温度 / 加熱時間 / 微細粒状金属 / プラズモン共鳴

Outline of Final Research Achievements

The annealing effect of thin pentacene and ultrathin gold/silver anode buffer layers on both the initial performance and durability against repetitive illumination stress in small-molecule organic solar cells (OSCs) was experimentally investigated. Repetitive illumination refers to 100 repetitions of a 3-s illumination and 27-s pause under darkness. OSCs with 0.3-nm-thick Au layer after annealing at Ta = 100°C provided both an initial power conversion efficiency comparable with OSCs without the anode buffer and an increase of 72% in durability. The ultrathin Au layer brought both a large absorption of ultraviolet light and highly dense nucleation sites for overlaid CuPc film formation. The latter would suppress the formation of a void at the interface between anode and donor and pinholes at the donor/acceptor junction driven by the increase in temperature during the illumination stress. These are possible reasons for durability improvement.

Academic Significance and Societal Importance of the Research Achievements

本研究では、真空蒸着プロセスを用いて精密に膜厚や組成を制御できる低分子型有機太陽電池を対象にして、アノード電極上や有機層中に配置したナノサイズの微細粒状金や銀の、大きさ、位置、面密度などを加熱処理で制御し、電力変換効率や光照射耐久性への期待される効果を検証した。微細粒状金や銀の導入による周辺有機媒質の結晶性の乱れなど、その負の側面をも明確に把握しながら、体系的なパラメータ調査と、そこから導かれる物理的メカニズムを明らかにすることは、今後の、この分野への基盤技術として重要である。

Research Products

• [Journal Article] Annealing effect of pentacene and ultrathin metal anode buffer on the performance of small-molecule organic solar cells (2021)
  • Author(s): Harafuji Kenji、Okada Takahiro
  • Journal Title: Thin Solid Films Volume: 723 Pages: 138581-138581
  • DOI: 10.1016/j.tsf.2021.138581
  • Peer Reviewed
• [Journal Article] Effect of a pentacene anode buffer on the performance of small-molecule organic solar cells (2019)
  • Author(s): Hanya Kazuhiro、Onaru Yukio、Harafuji Kenji
  • Journal Title: Solid-State Electronics Volume: 156 Pages: 62-72
  • DOI: 10.1016/j.sse.2019.03.028
  • Peer Reviewed
• [Presentation] 電極上の薄膜金銀の加熱処理が有機太陽電池の光照射耐久性に及ぼす効果 (2022)
  • Author(s): 服藤 憲司
  • Organizer: 2022年第69回応用物理学会春季学術講演会
• [Presentation] 薄膜金アノードバッファへの加熱処理が有機太陽電池の耐久性に及ぼす効果 (2021)
  • Author(s): 服藤憲司、岡田幸大
  • Organizer: 第68回応用物理学会春季学術講演会
• [Presentation] Stability Improvement in Organic Solar Cells with Annealed Pentacene/Gold Anode Buffer (2019)
  • Author(s): Kenji Harafuji and Takahiro Okada
  • Organizer: The 29th International Conference on Photovoltaic Science & Engineering (PVSEC-29)
  • Int'l Joint Research
• [Presentation] Annealed Thin Ag Layer on ITO Surface for Durability Improvement in Organic Solar Cells (2019)
  • Author(s): K.Otsuka, K.Harafuji
  • Organizer: 3rd International Conference on Applied Surface Science (ICASS)
  • Int'l Joint Research
• [Presentation] Durability Improvement of Organic Solar Cells with Ultra-thin Ag/Au Layers (2018)
  • Author(s): Kenji Harafuji, Takahiro Okada
  • Organizer: Advanced Energy Materials (AEM) 2018
  • Int'l Joint Research