Development of Bilayer-type Organic Electronic Materials for All-Printing Processes

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14699
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 35030:Organic functional materials-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Higashino Toshiki 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (30761324)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 有機半導体 / 有機トランジスタ / 層状結晶性 / 結晶構造制御 / 置換基効果 / トポケミカル反応 / 溶解性制御 / 耐熱性

Outline of Final Research Achievements

Herein, we demonstrate that engineered end-cap substitution for unsymmetric extended π-cores effectively achieves well-ordered two-dimensional (2D) molecular packing and thus realizes high-performance organic semi- conductors (OSCs). We developed phenyl- and decyl-substituted benzothieno- [6,5-b]benzothieno[3,2-b]thiophenes (BTBTTs) as solution-processable OSCs, providing layered single-crystalline thin-film transistors with a hole mobility of up to 12 cm2 V－1 s－1. The compound formed a bilayer-type layered herringbone packing in which the unsymmetric π-core aligned unidirectionally to form the respective molecular layers, owing to the well-balanced contributions of intermolecular interactions between the π-cores and between the respective end substituents. The eventual close intralayer molecular packing afforded a small effective mass and high thermal stability. These findings will be crucial for expanding the ability to develop high-performance OSCs.

Free Research Field

有機材料化学

Academic Significance and Societal Importance of the Research Achievements

本研究では，有機半導体材料が抱える全塗布プロセスへの適応性，すなわち塗布成膜した薄膜が後工程のさらなる重ね塗りに対して耐性を欠いていることに着目し，その解決を図るべく材料基盤技術の開発に取り組んだ．開発した材料は溶媒に不溶で，熱的安定性にも優れ，後工程に十分耐えうる性質を示したが，溶解性の調整機構が機能せず，塗布成膜への適性を欠いてしまった．本課題の直接的な解決には至らなかったものの，より根本的な課題の抽出に至り，目標を研究開始当初より修正し，その方針転換にそって半導体機能の向上につながる構造制御技術を見いだし，今後のプリンテッドエレクトロニクスの発展につながる成果をあげている．