Mukhopadhyay S, Topham B J, Soos Z G, Ramasesha S
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
J Phys Chem A. 2008 Aug 7;112(31):7271-9. doi: 10.1021/jp8012078. Epub 2008 Jul 17.
The photoluminescence (PL) and electroluminescence (EL) of thin films of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) are remarkably different. Similar PL and EL are instead observed in films of the closely related donors tri- p-tolylamine (TTA) and N, N'-diphenyl- N, N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD). Such films show a wide range of hole transport that depends on the morphology and on external parameters such as temperature and electric field. Restricted configuration-interaction calculations performed on TTA, TAPC, TPD, and radical ions of TTA indicate that the unusual EL of TAPC films is due to direct recombination from a low-lying charge-transfer (CT) state. The CT state is strongly stabilized by electrostatic interactions with the polar environment. Theory confirms that TAPC can be considered a dimer of TTA. The charge distributions of TTA (+) and TTA (-) indicate charge localization in the anion that rationalizes low electron mobility as well as a strong charge-induced-dipole stabilization of the CT state.
1,1-双[(二-4-甲苯基氨基)苯基]环己烷（TAPC）薄膜的光致发光（PL）和电致发光（EL）有显著差异。而在结构相近的供体三对甲苯胺（TTA）和N,N'-二苯基-N,N'-双(3-甲基苯基)-(1,1'-联苯)-4,4'-二胺（TPD）的薄膜中观察到了相似的PL和EL。这类薄膜表现出广泛的空穴传输特性，这取决于薄膜的形态以及诸如温度和电场等外部参数。对TTA、TAPC、TPD以及TTA的自由基离子进行的受限组态相互作用计算表明，TAPC薄膜不寻常的EL是由于来自低能电荷转移（CT）态的直接复合。CT态通过与极性环境的静电相互作用而得到强烈稳定。理论证实TAPC可被视为TTA的二聚体。TTA(+)和TTA(-)的电荷分布表明阴离子中的电荷局域化，这解释了低电子迁移率以及CT态的强电荷诱导偶极稳定作用。
