Schwarze Martin, Gaul Christopher, Scholz Reinhard, Bussolotti Fabio, Hofacker Andreas, Schellhammer Karl Sebastian, Nell Bernhard, Naab Benjamin D, Bao Zhenan, Spoltore Donato, Vandewal Koen, Widmer Johannes, Kera Satoshi, Ueno Nobuo, Ortmann Frank, Leo Karl
Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany.
Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany.
Nat Mater. 2019 Mar;18(3):242-248. doi: 10.1038/s41563-018-0277-0. Epub 2019 Jan 28.
Doped organic semiconductors typically exhibit a thermal activation of their electrical conductivity, whose physical origin is still under scientific debate. In this study, we disclose relationships between molecular parameters and the thermal activation energy (E) of the conductivity, revealing that charge transport is controlled by the properties of host-dopant integer charge transfer complexes (ICTCs) in efficiently doped organic semiconductors. At low doping concentrations, charge transport is limited by the Coulomb binding energy of ICTCs, which can be minimized by systematic modification of the charge distribution on the individual ions. The investigation of a wide variety of material systems reveals that static energetic disorder induced by ICTC dipole moments sets a general lower limit for E at large doping concentrations. The impact of disorder can be reduced by adjusting the ICTC density and the intramolecular relaxation energy of host ions, allowing an increase of conductivity by many orders of magnitude.
掺杂有机半导体通常表现出其电导率的热激活现象，其物理起源仍在科学辩论之中。在本研究中，我们揭示了分子参数与电导率的热激活能（E）之间的关系，表明在高效掺杂的有机半导体中，电荷传输由主体 - 掺杂剂整数电荷转移络合物（ICTC）的性质控制。在低掺杂浓度下，电荷传输受ICTC的库仑结合能限制，通过对单个离子上电荷分布的系统修饰可将其最小化。对多种材料体系的研究表明，由ICTC偶极矩引起的静态能量无序在大掺杂浓度下为E设定了一个普遍的下限。通过调整ICTC密度和主体离子的分子内弛豫能，可以降低无序的影响，从而使电导率提高多个数量级。
