Abstract
The polymorphic behavior of conjugated polymers enables tunable optoelectronic properties, but their transport mechanism remains elusive due to the inherent complexity and uncontrollability of polymorphic self-assembly behaviors and electronic processes at various length scales, alongside the ambiguous relationship between solution and solid states. Herein, precise control of multi-level supramolecular self-assembly of a polymorphic conjugated polymer, N-PDPP4T-HD with two distinct semi-crystalline aggregated phases (β1 and β2) via solvent engineering is demonstrated. β1 forms 1D worm-like nanostructures in solution, whereas β2 generates 2D nanoscale lamellar configuration, confirmed by experimental observation and molecular dynamic simulation. Such solution-state features are inherited in the solid state (1D nanofibers for β1 and 2D granular-like structures for β2). X-ray characterizations reveal larger crystalline domains on the nanometer scale, reduced π-stacking distance on the Ångstrom scale, and diminished paracrystallinity disorder for solid-state β2. Going beyond conventional DC transistor characterizations, contact-free ultrafast terahertz spectroscopy to unveil AC short-range, intrinsic transport properties is employed. Longer charge carrier scattering time and thus intrinsic mobility of β2 result in threefold higher short-range photoconductivity than β1. This work establishes the “solution structure – solid structure – local transport” relation in polymorphic conjugated polymers and provides new opportunities for high-performance plastic electronic devices.
Original language | English |
---|---|
Journal | Advanced Energy Materials |
DOIs | |
Publication status | E-pub ahead of print - 5 Aug 2024 |
Keywords
- charge transport
- conjugate polymers
- polymorphism
- supramolecular assembly
- terahertz spectroscopy