The Effects of Side Chains on the Charge Mobilities and Functionalities of Semiconducting Conjugated Polymers beyond Solubilities

Abstract

Recent decades have witnessed the rapid development of semiconducting polymers in terms of high charge mobilities and applications in transistors. Significant efforts have been made to develop various conjugated frameworks and linkers. However, studies are increasingly demonstrating that the side chains of semiconducting polymers can significantly affect interchain packing, thin film crystallinity, and thus semiconducting performance. Ways to modify the side alkyl chains to improve the interchain packing order and charge mobilities for conjugated polymers are first discussed. It is shown that modifying the branching chains by moving the branching points away from the backbones can boost the charge mobilities, which can also be improved through partially replacing branching chains with linear ones. Second, the effects of side chains with heteroatoms and functional groups are discussed. The siloxane‐terminated side chains are utilized to enhance the semiconducting properties. The fluorinated alkyl chains are beneficial for improving both charge mobility and air stability. Incorporating H bonding group side chains can improve thin film crystallinities and boost charge mobilities. Notably, incorporating functional groups (e.g., glycol, tetrathiafulvalene, and thymine) into side chains can improve the selectivity of field‐effect transistor (FET)‐based sensors, while photochromic group containing side chains in conjugated polymers result in photoresponsive semiconductors and optically tunable FETs.

A Structurally Simple but High‐Performing Donor–Acceptor Polymer for Field‐Effect Transistor Applications

“…Both polymers containing the more synthetically complex 5DH sidechains exhibited lower performance than their simpler 2DT analogs when annealed at 100 °C, by a factor of 3 for the T2 polymers and almost an order of magnitude for the TVT polymers. We note that although most studies have found that moving the branching point further away from the conjugated polymer backbone resulted in reduced π–π stacking distance in agreement with these results, [ 41–45 ] this has not always correlated to an improved charge carrier mobility, as observed here. [ 42,52,53 ] Several studies have also highlighted a pronounced odd–even effect with regard to the length of the spacer chain between the backbone and the branching point.…”

Recent Advances in Flexible Field‐Effect Transistors toward Wearable Sensors

“…The low-bandgap conjugated polymer's side chain materials demonstrated excellent mechanical properties and acceptable electronic performances. [257,258] In addition to the utilization of polymers with side chains in molecular structures, copolymers, which enable the combination of different functional monomers, drew the attention of researchers for performance optimizations. By integrating biodegradable materials into the block of stretchable semiconducting materials, researchers have fabricated FET sensors with optimized detecting performances.…”

“…The low‐bandgap conjugated polymer's side chain materials demonstrated excellent mechanical properties and acceptable electronic performances. [ 257,258 ]…”

More Interaction Sites and Enhanced Fluorescence for Highly Sensitive Fluorescence Detection of Methamphetamine Vapor via Sidechain Terminal Functionalization of Conjugated Polymers

“…To solve this problem, an effective strategy is to introduce side chains with large spatial structures or rigid structures to obtain polymers with stronger fluorescence in solid state, in which the space‐crowded structure helps weaken the ACQ effect by inhibiting the strong intermolecular interactions. At the same time, side chain modification is also an effective method to adjust morphology . For instance, Bao et al.…”