Chernyshov Ivan Yu, Vener Mikhail V, Feldman Elizaveta V, Paraschuk Dmitry Yu, Sosorev Andrey Yu
Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences , Leninskii prosp. 31, Moscow 119991, Russia.
G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences , Academicheskaya 1, 153045 Ivanovo, Russia.
J Phys Chem Lett. 2017 Jul 6;8(13):2875-2880. doi: 10.1021/acs.jpclett.7b01003. Epub 2017 Jun 13.
Organic electronics requires materials with high charge mobility. Despite decades of intensive research, charge transport in high-mobility organic semiconductors has not been well understood. In this Letter, we address the physical mechanism underlying the exceptionally high band-like electron mobility in F-TCNQ (2,5-difluoro-7,7,8,8-tetracyanoquinodimethane) single crystals among a crystal family of similar compounds F-TCNQ (n = 0, 2, 4) using a combined experimental and theoretical approach. While electron transfer integrals and reorganization energies did not show outstanding features for F-TCNQ, Raman spectroscopy and solid-state DFT indicated that the frequency of the lowest vibrational mode is nearly twice higher in the F-TCNQ crystal than in TCNQ and F-TCNQ. This phenomenon is explained by the specific packing motif of F-TCNQ with only one molecule per primitive cell so that electron-phonon interaction decreases and the electron mobility increases. We anticipate that our findings will encourage investigators for the search and design of organic semiconductors with one molecule per primitive cell and/or the poor low-frequency vibrational spectrum.
有机电子学需要具有高电荷迁移率的材料。尽管经过了数十年的深入研究，但高迁移率有机半导体中的电荷传输仍未得到很好的理解。在本信函中，我们采用实验与理论相结合的方法，探讨了在类似化合物F-TCNQ（n = 0, 2, 4）晶体家族中，F-TCNQ（2,5-二氟-7,7,8,8-四氰基对苯二醌二甲烷）单晶中异常高的带状电子迁移率背后的物理机制。虽然F-TCNQ的电子转移积分和重组能没有表现出突出特征，但拉曼光谱和固态密度泛函理论表明，F-TCNQ晶体中最低振动模式的频率几乎比TCNQ和F-TCNQ中的高出一倍。这种现象可以通过F-TCNQ的特定堆积模式来解释，即每个原胞中只有一个分子，从而使电子-声子相互作用减弱，电子迁移率增加。我们预计，我们的发现将鼓励研究人员寻找和设计每个原胞中有一个分子和/或低频振动光谱较差的有机半导体。
