主、侧链修饰对异靛蓝基共轭聚合物结构及电学性能的影响

Effects of modification of main and side chains on the structure and electrical properties of isoindigo-based conjugated polymers

研究了基于异靛蓝及其衍生物的给-受体共轭聚合物主、侧链修饰对电学性能的影响。采用掠入射X射线衍射、原子力显微镜和4200半导体参数测试仪对聚合物结构与形貌以及电学性能进行了表征。实验结果表明,烷基侧链的加入会增大空间位阻,使得分子堆积从较为有序的edge-on结构变得混乱无序,导致结晶性和电学性能的下降。平均空穴迁移率从0.05 cm 2 ·V -1 ·s -1 下降至2.11×10 -3 cm 2 ·V -1 ·s -1 。但当主链用苯并二呋喃二酮(BIBDF)这一强吸电子的长共轭单元替代异靛蓝单元之后,由于主链平面性的提高,引起分子堆积变好,结晶性和电学性能显著提高,并不影响溶液加工性且该聚合物显示出良好的双极型传输特性。空气中电子与空穴平均迁移率可以达到0.29 cm 2 ·V -1 ·s -1 和0.49 cm 2 ·V -1 ·s -1 。

The effects of main and side chain modification of donor-acceptor conjugated polymers based on isoindigo and its derivatives on electrical properties were studied. The structure, morphology and electrical properties of the polymers were characterized by glancing angle X-ray diffraction, atomic force microscopy and Keithley 4200-SCS. The experimental results show that the addition of alkyl side chains can increase the steric hindrance and change the molecular stacking from the ordered edge-on structure to disordered, resulting in the decrease of crystallinity and electrical properties. The average hole mobility decreased from 0.05 cm 2 ·V -1 ·s -1 to 2.11 × 10 -3 cm 2 ·V -1 ·s -1 . However, when the long conjugated unit of benzofuradiadione (BIBDF) is used to replace the isoindigo unit in the main chain, the molecular stacking, crystallinity and electrical properties of the main chain are improved significantly due to the improvement of the planarity of the main chain, which don’t affect the solution processability, and the polymer shows good bipolar transmission characteristics. The average mobility of electron and hole can reach to 0.29 cm 2 ·V -1 ·s -1 and 0.49 cm 2 ·V -1 ·s -1 .