Charge generation, recombination, and transport in organic semiconductors are fundamental processes that dictate the performance for a range of organic devices. Here we used electrostatic force microscopy combined with laser scanning microscopy to study the carrier distribution in individual organic nanofibers that result from localized illumination: NaT₂ (5,5′-bis(naphth-2-yl)-2,2′-bithiophene) crystalline nanofibers were illuminated with a continuous wave, focused laser beam with above-band gap photon energy. The localized illumination causes a local negative charge accumulation at the illumination position, while the remaining part of the nanofiber exhibits a positive charge. We propose that this inhomogeneous distribution of photogenerated holes and electrons along the nanofiber axis is due to a surface-trap induced exciton dissociation and the difference in charge carrier mobilities for hole and electrons. We use a one-dimensional, drift-diffusion based model to rationalize the observations and give an improved understanding of the factors governing the charge build-up.

有机半导体中的电荷产生，复合和传输是决定一系列有机器件性能的基本过程。在这里，我们将静电力显微镜与激光扫描显微镜相结合，研究了局部照明产生的单个有机纳米纤维中的载流子分布：NaT ₂（5,5'-双（萘-2-基）-2,2'-联噻吩）晶体纳米纤维被连续波聚焦激光束以带隙光子能量照射。局部照明在照明位置导致局部负电荷积累，而纳米纤维的其余部分则呈现正电荷。我们提出光生空穴和电子沿着纳米纤维轴的这种不均匀分布是由于表面陷阱引起的激子解离以及空穴和电子的载流子迁移率的差异。我们使用一维，基于漂移扩散的模型来合理化观测值，并更好地理解控制电荷积累的因素。