取向可控的并五苯、[6]并菲和[7]并菲薄膜的电离能、电子亲和能、带隙、激子结合能及极化能
Ionization Energies, Electron Affinities, Bandgaps, Exciton Binding Energies, and Polarization Energies of Orientation-Controlled Picene, [6]-Phenacene, and [7]-Phenacene Thin Films
AI总结：
本研究测定取向可控的并五苯、[6]并菲和[7]并菲薄膜的多种电子参数，发现分子取向是调控其前沿能级的关键因素，IE和EA随取向呈约1 eV的大幅偏移。
AI中文摘要：
并菲是一类以锯齿形方式稠合苯环的化学稳定π共轭烃，在有机电子应用和超导电性领域备受关注。但与并苯相比，其薄膜的定量电子参数仍较为有限。本研究采用紫外光电子能谱和低能逆光电子能谱，测定了取向可控的并五苯、[6]并菲和[7]并菲薄膜的电离能（IEs）、电子亲和能（EAs）、带隙、激子结合能及极化能。结果显示，这些能量参数仅微弱依赖于分子尺寸；相反，IE和EA均表现出约1 eV的大取向相关偏移：平躺薄膜的IE为6.41-6.43 eV、EA为2.16-2.42 eV，而直立薄膜的IE为5.44-5.67 eV、EA为1.36-1.53 eV。不过，约4 eV的带隙和约1 eV的激子结合能几乎不依赖于分子尺寸和取向。极化能分析表明，诱导项几乎与取向无关，而静电项则强烈依赖于取向，且主要源于分子四极矩。这些结果表明，分子取向是控制并菲薄膜前沿能级的关键因素。
英文摘要：
Phenacenes, in which benzene rings are fused in a zigzag manner, are chemically robust $π$-conjugated hydrocarbons of interest for organic electronic applications and superconductivity. However, quantitative electronic parameters of phenacene thin films remain limited compared with those of acenes. Here, we determine the ionization energies (IEs), electron affinities (EAs), band gaps, exciton binding energies, and polarization energies of orientation-controlled thin films of picene, [6]-phenacene, and [7]-phenacene using ultraviolet photoelectron spectroscopy and low-energy inverse photoelectron spectroscopy. The energy parameters depend only weakly on molecular size. In contrast, both IE and EA exhibit large orientation-dependent shifts of approximately 1 eV: lying films show IEs of 6.41-6.43 eV and EAs of 2.16-2.42 eV, whereas standing films show IEs of 5.44-5.67 eV and EAs of 1.36-1.53 eV. Nevertheless, the band gaps of approximately 4 eV and exciton binding energies of approximately 1 eV remain nearly independent of molecular size and orientation. Analysis of polarization energies shows that the induction term is nearly orientation independent, whereas the electrostatic term strongly depends on orientation and originates primarily from molecular quadrupole moments. These results identify molecular orientation as a key factor governing frontier energy levels in phenacene thin films.
