Nakayama Yasuo, Mizuno Yuta, Hikasa Masataka, Yamamoto Masayuki, Matsunami Masaharu, Ideta Shinichiro, Tanaka Kiyohisa, Ishii Hisao, Ueno Nobuo
Department of Pure and Applied Chemistry, Graduate School of Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda 278-8510, Japan.
Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
J Phys Chem Lett. 2017 Mar 16;8(6):1259-1264. doi: 10.1021/acs.jpclett.7b00082. Epub 2017 Mar 3.
The electronic structures of the highest occupied molecular orbital (HOMO) or the HOMO-derived valence bands dominate the transport nature of positive charge carriers (holes) in organic semiconductors. In the present study, the valence-band structures of single-crystal pentacene and the temperature dependence of their energy-momentum dispersion relations are successfully demonstrated using angle-resolved ultraviolet photoelectron spectroscopy (ARUPS). For the shallowest valence band, the intermolecular transfer integral and effective mass of the holes are evaluated as 43.1 meV and 3.43 times the electron rest mass, respectively, at room temperature along the crystallographic direction for which the widest energy dispersion is expected. The temperature dependence of the ARUPS results reveals that the transfer integral values (hole effective mass) are enhanced (reduced) by ∼20% on cooling the sample to 110 K.
最高占据分子轨道（HOMO）或源自HOMO的价带的电子结构主导着有机半导体中正电荷载流子（空穴）的传输性质。在本研究中，利用角分辨紫外光电子能谱（ARUPS）成功地展示了单晶并五苯的价带结构及其能量 - 动量色散关系的温度依赖性。对于最浅的价带，在室温下沿着预期具有最宽能量色散的晶体学方向，空穴的分子间转移积分和有效质量分别评估为43.1毫电子伏特和电子静止质量的3.43倍。ARUPS结果的温度依赖性表明，将样品冷却至110 K时，转移积分值（空穴有效质量）增加（降低）了约20%。
