A Thiophene Backbone Enables Two‐Dimensional Poly(arylene vinylene)s with High Charge Carrier Mobility
Yamei Liu, Heng Zhang, Hongde Yu, Zhongquan Liao, Silvia Paasch, Shunqi Xu, Ruyan Zhao, Eike Brunner, Mischa Bonn, Hai I. Wang, Thomas Heine, Mingchao Wang, Yiyong Mai, Xinliang Feng
Abstract
Abstract Linear conjugated polymers have attracted significant attention in organic electronics in recent decades. However, despite intrachain π‐delocalization, interchain hopping is their transport bottleneck. In contrast, two‐dimensional (2D) conjugated polymers, as represented by 2D π‐conjugated covalent organic frameworks (2D c ‐COFs), can provide multiple conjugated strands to enhance the delocalization of charge carriers in space. Herein, we demonstrate the first example of thiophene‐based 2D poly(arylene vinylene)s (PAVs, 2DPAV‐BDT‐BT and 2DPAV‐BDT‐BP , BDT=benzodithiophene, BT=bithiophene, BP=biphenyl) via Knoevenagel polycondensation. Compared with 2DPAV‐BDT‐BP , the fully thiophene‐based 2DPAV ‐ BDT ‐ BT exhibits enhanced planarity and π‐delocalization with a small band gap (1.62 eV) and large electronic band dispersion, as revealed by the optical absorption and density functional calculations. Remarkably, temperature‐dependent terahertz spectroscopy discloses a unique band‐like transport and outstanding room‐temperature charge mobility for 2DPAV‐BDT‐BT (65 cm 2 V −1 s −1 ), which far exceeds that of the linear PAVs, 2DPAV‐BDT‐BP , and the reported 2D c ‐COFs in the powder form. This work highlights the great potential of thiophene‐based 2D PAVs as candidates for high‐performance opto‐electronics.