Charge-carrier transport in oriented COF thin films is an important factor for realizing COF-based optoelectronic devices. We describe how highly oriented electron-donating benzodithiophene BDT-COF thin films serve as a model system for a directed charge-transport study. Oriented BDT-COF films were deposited on different electrodes with excellent control over film roughness and topology, allowing for high-quality electrode–COF interfaces suitable for device fabrication. Hole-only devices were constructed to study the columnar hole mobility of the BDT-COF films. The transport measurements reveal a clear dependency of the measured hole mobilities on the BDT-COF film thickness, where thinner films showed about two orders of magnitude higher mobilities than thicker ones. Transport measurements under illumination yielded an order of magnitude higher mobility than in the dark. In-plane electrical conductivity values of up to 5 × 10–7 S cm–1 were obtained for the oriented films. Impedance measurements of the hole-only devices provided further electrical description of the oriented BDT-COF films in terms of capacitance, recombination resistance,and dielectric constant. An exceptionally low dielectric constantvalue of approximately 1.7 was estimated for the BDT-COF films, afurther indication of their highly porous nature. DFT and molecular-dynamicssimulations were carried out to gain further insights into the relationshipsbetween the COF layer interactions, electronic structure, and thepotential device performance.
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机译:定向COF薄膜中的载流子传输是实现基于COF的光电器件的重要因素。我们描述高度取向的给电子苯并二噻吩BDT-COF薄膜如何作为定向电荷传输研究的模型系统。定向的BDT-COF薄膜沉积在不同的电极上,可以很好地控制薄膜的粗糙度和拓扑结构,从而提供适合设备制造的高质量电极-COF界面。构造仅空穴的装置以研究BDT-COF膜的柱状空穴迁移率。传输测量结果表明,所测量的空穴迁移率与BDT-COF薄膜厚度有明显的相关性,其中较薄的薄膜显示的迁移率比较厚的薄膜高约两个数量级。光照条件下的迁移率测量结果比黑暗条件下的迁移率高一个数量级。取向膜的面内电导率值最高为5×10 –7 sup> S cm –1 sup>。仅孔器件的阻抗测量提供了有关定向BDT-COF薄膜的电学描述,包括电容量,复合电阻,和介电常数。介电常数极低BDT-COF膜的估计值约为1.7,进一步说明了它们的高度多孔性。 DFT和分子动力学进行模拟以获得对关系的进一步了解COF层之间的相互作用,电子结构和潜在的设备性能。
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