Side-chain engineering of semiconducting polymers with poly(benzyl ether) dendrons: impact on electronic and mechanical properties

Abstract

The rise of organic electronics is unlocking exciting possibilities for the development of flexible, sustainable, and energy-efficient technologies. From wearable devices and intelligent food packaging to light-harvesting materials and smart textiles, these innovations are driving the next establishment of the Internet of Things (IoT) and other AI-driven autonomous systems, where interconnected devices and intelligent technologies seamlessly work together to transform industries and daily life. At the core of these emerging technologies are semiconducting polymers, which offer a unique combination of synthetic tunability, solution processability, and tuneable optoelectronic and mechanical properties. These features pave the way for cutting-edge fabrication techniques—such as 3D and inkjet printing—to create high-performance devices. Achieving solution processability in these polymer systems often requires the incorporation of bulky, acyclic aliphatic side chains, amongst many others, to enhance solubility and mitigate strong molecular aggregation. These side chains can significantly impact multiple properties, including charge carrier mobility through their influence on the polymer nanostructure in thin films. This work explores the utilization of dendronized side chains to modulate the properties of semicrystalline polymers. More precisely, we developed a new series of materials by integrating high-performance diketopyrrolopyrrole (DPP)-based backbones with two distinct poly(benzyl ether) side chains and two different donor units. These structural variations were found to significantly influence processing conditions, as well as the electronic and thermomechanical properties of the resulting polymers. Comprehensive characterization, including grazing incidence wide-angle X-ray scattering (GIWAXS), atomic force microscopy (AFM), quantitative nanomechanical mapping (for Young's moduli), and dynamic mechanical analysis (DMA) to determine glass transitions, was performed. The polymers were subsequently employed in the fabrication of organic field-effect transistors (OFETs) to study their impact on the electronic properties. The incorporation of novel dendron-like side chains provides a promising strategy for advancing side-chain engineering in semiconducting polymers, offering new avenues in the development of emerging printed organic electronics.