Molecular-dipole oriented universal growth of conjugated polymers into semiconducting single-crystal thin films

Abstract

Precise control over crystallinity and morphology of conjugated polymers (CPs) is essential for progressing organic electronics. However, manufacturing single-crystal thin films of CPs presents substantial challenges due to their complex molecular structures, distorted chain conformations, and unbalanced crystallization kinetics. In this work, we demonstrate a universal nanoconfined molecular-dipole orientating strategy to craft high-quality single-crystal thin films for a variety of CPs, spanning from traditional thiophene- and theinothiophene-based homopolymers to diketopyrrolopyrrole- (i.e., p-type) and naphthalene-based (i.e., n-type) donor-acceptor copolymers. Central to this strategy is the synergetic manipulations of molecular dipoles, π-π stackings, and alkyl-alkyl interactions of CPs within our rationally-designed spatial-electrostatic confinement capacitor, which facilitates the rotation of conjugated backbones and the alignment of π-π stackings into microscale-sized single-crystal thin films. A minimal energetic disorder of 25 meV that below the thermal fluctuation energy k_BT at room temperature, as well as an excellent transistor mobility of 15.5 cm²V⁻¹s⁻¹ are achieved, marking a significant step towards controllable growths of conjugated-polymer single-crystal thin films that hold a cornerstone for high-performance organic electronic devices.