Tuning Dielectric Constant of P3HT by Ultrasound-Induced Aggregation

Abstract

Poly(3-hexylthiophene) (P3HT), a semiconducting polymer, is integral to the development of organic electronic devices. Its optoelectronic properties are significantly influenced by the nature of its intermolecular interactions, predominantly classified as J-type and H-type couplings. This study investigates the effect of sonication on the dielectric properties of P3HT, focusing on the transition from J-type (or less prominent H-type) to H-type intermolecular interactions, accompanied by disorder-order transformation. The research determined that sonication leads to a significant change in the dielectric properties of P3HT by forming distinct ordered regions interspersed within disordered or quasi-ordered areas. Specifically, there is an observable transition from J-type to H-type aggregation, which has profound effects on the material's electronic structure and optoelectronic performance. This transition was confirmed by changes in the absorption and photoluminescence spectra, indicating a more localized electronic character and the formation of non-emissive excitons in the case of H-aggregates. Increased dielectric constant after sonication is attributed to interface polarization, especially the Maxwell-Wagner-Sillars polarization. This effect is likely because new interfaces are created between the ordered regions and disordered/quasi-ordered regions within the P3HT material, where charges can accumulate as a result of disorder-order transformation. Our research contributes to the broader understanding of polymer physics and the development of organic electronic devices by showing how the manipulation of microstructural environments can control material properties.