Chen Hu, Wadsworth Andrew, Ma Chun, Nanni Alice, Zhang Weimin, Nikolka Mark, Luci Alexander M T, Perdigão Luís M A, Thorley Karl J, Cendra Camila, Larson Bryon, Rumbles Garry, Anthopoulos Thomas D, Salleo Alberto, Costantini Giovanni, Sirringhaus Henning, McCulloch Iain
King Abdullah University of Science and Technology (KAUST) , KAUST Solar Center (KSC) , Thuwal 23955-6900 , Saudi Arabia.
Department of Chemistry and Centre for Plastic Electronics , Imperial College London , Exhibition Road , London SW7 2AZ , United Kingdom.
J Am Chem Soc. 2019 Nov 27;141(47):18806-18813. doi: 10.1021/jacs.9b09367. Epub 2019 Nov 18.
A fused donor, thienobenzo[]indacenodithiophene (), was designed and synthesized using a novel acid-promoted cascade ring closure strategy, and then copolymerized with a benzothiadiazole () monomer. The backbone of is an expansion of the well-known indacenodithiophene () unit and was expected to enhance the charge carrier mobility by improving backbone planarity and facilitating short contacts between polymer chains. However, the optimized field-effect transistors demonstrated an average saturation hole mobility of 0.9 cm V s, lower than the performance of (∼1.5 cm V s). Mobilities extracted from time-resolved microwave conductivity measurements were consistent with the trend in hole mobilities in organic field-effect transistor devices. Scanning tunneling microscopy measurements and computational modeling illustrated that exhibits a less ordered microstructure in comparison to . This reveals that a regular side-chain packing density, independent of conformational isomers, is critical to avoid local free volume due to irregular packing, which can host trapping impurities. DFT calculations indicated that , despite containing a larger, planar unit, showed less stabilization of planar backbone geometries in comparison to . This is due to the reduced electrostatic stabilizing interactions between the peripheral thiophene of the fused core and the unit, resulting in a reduction of the barrier to rotation around the single bond. These insights provide a greater understanding of the general structure-property relationships required for semiconducting polymer repeat units to ensure optimal backbone planarization, as illustrated with -type units, guiding the design of novel semiconducting polymers with extended fused backbones for high-performance field-effect transistors.
采用一种新型的酸促进级联闭环策略设计并合成了一种稠合供体噻吩并苯并[]茚并二噻吩（），然后将其与苯并噻二唑（）单体共聚。的主链是著名的茚并二噻吩（）单元的扩展，预计通过提高主链平面性和促进聚合物链之间的短程接触来提高载流子迁移率。然而，优化后的场效应晶体管的平均饱和空穴迁移率为0.9 cm² V⁻¹ s⁻¹，低于（~1.5 cm² V⁻¹ s⁻¹）的性能。从时间分辨微波电导率测量中提取的迁移率与有机场效应晶体管器件中空穴迁移率的趋势一致。扫描隧道显微镜测量和计算建模表明，与相比，具有较无序的微观结构。这表明，与构象异构体无关的规则侧链堆积密度对于避免由于不规则堆积导致的局部自由体积至关重要，因为不规则堆积会容纳捕获杂质。密度泛函理论计算表明，尽管包含更大的平面单元，但与相比，平面主链几何结构的稳定性较低。这是由于稠合核的外围噻吩与单元之间的静电稳定相互作用减弱，导致围绕单键旋转的势垒降低。这些见解有助于更深入地理解半导体聚合物重复单元所需的一般结构-性能关系，以确保最佳的主链平面化，如型单元所示，指导设计具有扩展稠合主链的新型半导体聚合物，用于高性能场效应晶体管。
