Control of dipole at electrode interface using polar molecules and improvement carrier injection into OLED devices

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K04465
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: University of Toyama
• Principal Investigator: Morimoto Masahiro 富山大学, 学術研究部工学系, 准教授 (90717290)
• Co-Investigator(Kenkyū-buntansha): 中 茂樹 富山大学, 学術研究部工学系, 教授 (50242483)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 有機EL / 極性分子 / ダイポール / 注入障壁 / P(VDF/TrFE)

Outline of Final Research Achievements

Organic light-emitting diode devices have been rapidly gaining popularity in recent years and are expected to be used not only for displays but also for a wide range of other applications such as lighting and lasers. Injection of electrons and holes from the electrode to the organic semiconductor layer is essential to drive the devices, but there are still many issues to be solved in terms of device efficiency. This research aims to improve charge injection by placing an electric dipole at an interface between the electrode and the organic semiconductor. As a result, devices with interfacial dipoles have improved performance, and further improvement has been confirmed by controlling the structure of the dipole layer. In addition, we were able to calculate the energy barrier height during charge injection by various measurements and obtained corroboration not only from the device measurement but also from physicochemical approaches.

Free Research Field

有機エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究では広く利用されている有機ELデバイスの課題の一つである、電極からのキャリア注入効率向上を目的にしている。電極/半導体界面の電荷移動は有機半導体に限らず無機半導体においても長く議論されてきた課題であり、課題解決にともなうデバイス性能向上には大きく期待できる。研究結果からもデバイス性能向上が示唆されており、爆発的な普及を遂げつつある有機ELデバイスへの影響は計り知れない。本成果は特殊な極性材料を用いた成果に加え、汎用的なポリマー材料においても同様の成果が得られており、今後のデバイス設計指針の一つになり得るだろう。