Nakayama Yasuo, Tsuruta Ryohei, Moriya Naoki, Hikasa Masataka, Meissner Matthias, Yamaguchi Takuma, Mizuno Yuta, Suzuki Toshiyasu, Koganezawa Tomoyuki, Hosokai Takuya, Ueba Takahiro, Kera Satoshi
Department of Pure and Applied Chemistry , Tokyo University of Science , 2641 Yamazaki , Noda 278-8510 , Japan.
Institute for Molecular Science (IMS) , National Institutes of Natural Sciences , 38 Nishigo-Naka , Myodaiji, Okazaki 444-8585 , Japan.
J Phys Chem Lett. 2019 Mar 21;10(6):1312-1318. doi: 10.1021/acs.jpclett.8b03866. Epub 2019 Mar 7.
Strong intermolecular electronic coupling and well-ordered molecular arrangements enable efficient transport of both charge carriers and excitons in semiconducting π-conjugated molecular solids. Thus, molecular heteroepitaxy to form crystallized donor-acceptor molecular interfaces potentially leads to a novel strategy for creating efficient organic optoelectronic devices via the concomitance of these two requirements. In the present study, the crystallographic and electronic structures of a heteroepitaxial molecular interface, perfluoropentacene (PFP, CF) grown on pentacene single crystals (Pn-SCs, CH), were determined by means of grazing-incidence X-ray diffraction (GIXD) and angle-resolved ultraviolet photoelectron spectroscopy (ARUPS), respectively. GIXD revealed that PFP uniquely aligned its primary axis along the [11̅0] axis of crystalline pentacene to form well-crystallized overlayers. Valence band dispersion (at least 0.49 eV wide) was successfully resolved by ARUPS. This indicated a significant transfer integral between the frontier molecular orbitals of the nearest-neighbor PFP molecules.
强分子间电子耦合和有序的分子排列使得电荷载流子和激子在半导体π共轭分子固体中能够高效传输。因此，通过分子异质外延形成结晶的供体-受体分子界面，有可能通过满足这两个条件，为制造高效有机光电器件带来一种新策略。在本研究中，通过掠入射X射线衍射（GIXD）和角分辨紫外光电子能谱（ARUPS）分别测定了在并五苯单晶（Pn-SCs，CH）上生长的异质外延分子界面——全氟并五苯（PFP，CF）的晶体结构和电子结构。GIXD显示，PFP独特地将其主轴沿结晶并五苯的[11̅0]轴排列，形成了结晶良好的覆盖层。通过ARUPS成功解析了价带色散（至少0.49 eV宽）。这表明最近邻PFP分子的前沿分子轨道之间存在显著的转移积分。
