Verification of band transport mechanism in organic semiconductors by observing free carriers

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05129
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Wakayama University
• Principal Investigator: Akimoto Ikuko 和歌山大学, システム工学部, 准教授 (00314055)
• Co-Investigator(Kenkyū-buntansha): 中 暢子 京都大学, 理学研究科, 准教授 (10292830)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 有機半導体 / 無機半導体 / 光キャリア / 伝導機構 / サイクロトロン共鳴

Outline of Final Research Achievements

We investigated transport properties of optically injected carriers in a high-mobility organic semiconductor, rubrene crystal, in comparison to those in non-organic semiconductors, with the aim of demonstrating the band transport mechanism in the organic system. First, we confirmed that optical carrier injection is established by the dissociation of excitons induced by electric field, based on an observation of anti-correlation between exciton luminescence and photocurrent. In contract, we found that all optical carrier injection pathways via (i) the band-to-band transition and (ii) exciton dissociation in pure silicon and diamond crystals. Second, we performed the time-resolved cyclotron resonance measurement for carriers generated by two-photon excitation in rubrene crystals. A spectrum observed at 2.5 K indicated a peak centered at the effective mass of 0.23 m0, but the value was still unreliable because of the puzzling dependence on temperature and crystal orientation.

Free Research Field

数物系科学