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Research

Keywords

organic semiconductors, π-conjugated polymers, molecular orientation

PublicationsNIMS affiliated publications since 2004.

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Society memberships

応用物理学会, 高分子学会

Research Center for Macromolecules and Biomaterials
Title

Development of new organic semiconductors and their application in thin-film devices

Keywords

Organic semiconductors, conjugated polymers, and organic thin-film devices

Overview

Organic light-emitting diodes (OLEDs) based on organic thin films have been commercialized using small-molecule semiconductors that can be fabricated by vacuum deposition. However, further development of polymer semiconductors, which are suitable for solution-based film formation, is highly desired. In addition to OLEDs, the commercialization of organic thin-film transistors (OTFTs) and organic thin-film solar cells requires the development of advanced organic semiconductors. For successful materials development, it is essential to rapidly and efficiently evaluate the properties of new organic semiconductors and device characteristics, and to provide timely feedback to the synthesis process. In this research, we select the most appropriate organic thin-film device and optimize its structure according to the properties of the organic semiconductor.

Novelty and originality

Fabrication of organic thin-film devices utilizing the unique properties of new organic semiconductors
Performance enhancement through device structure optimization
Carrier mobility measurements of organic semiconductor films via diode characterization
Structural evaluation of organic semiconductor films through emission spectrum analysis

Details

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A representative example of new organic semiconductors is the fabrication and evaluation of organic thin-film devices using anthracene derivatives. The n-type semiconductor 2,6-DPA-F, featuring a pentafluorophenyl group with strong electron-accepting properties, was employed in OTFTs. Optimizing the device structure by replacing Ag electrodes with low work-function Mg resulted in high electron mobility of 0.12 cm²V⁻¹s⁻¹.
In contrast, vacuum-deposited films of TAAnt1 showed amorphous characteristics and a fluorescence quantum yield of 29%. Employing TAAnt1 as the emissive material in OLEDs, and optimizing the device structure by sandwiching the emission layer between the hole (HTL) and electron (ETL) transport layers, led to improved emission efficiency.

A specialized textbook on device physics for high-performance OLEDs has also been published (Japanese edition: Maruzen Publishing 2023; English edition: Wiley 2026). The book explains the operating principles of multilayer OLEDs using glassy amorphous organic semiconductors, and covers key topics such as tandem structures, exciplexes, molecular orientation, as well as uniquely important aspects for OLEDs, such as luminance degradation and operational lifetime.

Summary

Comprehensive evaluation of energy levels, fluorescence quantum yield, and crystallinity of organic semiconductors to fabricate optimal organic thin-film devices
Enhancement of device performance through structural optimization of organic thin-film devices
Further development of coating materials for OLEDs, OTFTs, and organic thin-film solar cells, which have not yet been commercialized

この機能は所内限定です。
この機能は所内限定です。

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