Neelamraju Bharati, Watts Kristen E, Pemberton Jeanne E, Ratcliff Erin L
J Phys Chem Lett. 2018 Dec 6;9(23):6871-6877. doi: 10.1021/acs.jpclett.8b03104. Epub 2018 Nov 21.
Understanding the interaction between organic semiconductors (OSCs) and dopants in thin films is critical for device optimization. The proclivity of a doped OSC to form free charges is predicated on the chemical and electronic interactions that occur between dopant and host. To date, doping has been assumed to occur via one of two mechanistic pathways: an integer charge transfer (ICT) between the OSC and dopant or hybridization of the frontier orbitals of both molecules to form a partial charge transfer complex (CPX). Using a combination of spectroscopies, we demonstrate that CPX and ICT states are present simultaneously in FTCNQ-doped P3HT films and that the nature of the charge transfer interaction is strongly dependent on the local energetic environment. Our results suggest a multiphase model, where the local charge transfer mechanism is defined by the electronic driving force, governed by local microstructure in regioregular and regiorandom P3HT.
了解有机半导体（OSC）与薄膜中的掺杂剂之间的相互作用对于器件优化至关重要。掺杂的OSC形成自由电荷的倾向取决于掺杂剂与主体之间发生的化学和电子相互作用。迄今为止，人们认为掺杂是通过两种机制途径之一发生的：OSC与掺杂剂之间的整数电荷转移（ICT）或两个分子的前沿轨道杂化以形成部分电荷转移络合物（CPX）。通过光谱学方法的结合，我们证明CPX和ICT态同时存在于FTCNQ掺杂的P3HT薄膜中，并且电荷转移相互作用的性质强烈依赖于局部能量环境。我们的结果提出了一个多相模型，其中局部电荷转移机制由电子驱动力定义，该驱动力由区域规整和区域无规P3HT中的局部微观结构控制。
