Effect of Polymer Chain Folding on the Transition from H- to J-Aggregate Behavior in P3HT Nanofibers

Abstract

A combination of wavelength-, time-, and polarizationresolved photoluminescence imaging on isolated P3HT nanofibers of varying molecular weight (from 10 to 65 kDa) has revealed a transition in dominant exciton coupling from primarily interchain (H-aggregation) for low molecular weight nanofibers, to predominantly intrachain (Jaggregation) coupling for high molecular weight nanofibers. Based on nanofiber width measurement from TEM imaging, the driving force for this transition appears to be folding of individual polymer chains within the lamellae, resulting in enhanced chain planarity and reduced torsional disorder.

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

“…The thin film UV–visible absorption of polythiophene derivatives can provide some information about the molecular order of the polymer chains, via the interpretation of the vibronic shoulders [52–55]. In the case of mixtures and block copolymers this is somewhat complicated by the different overlapping absorption profiles of the components.…”

“…In the case of F-P3OT, annealing just under the melting onset (238 °C) leads to a significant shift in the vibronic structure. The large increase in the intensity of the high-energy part of the spectrum suggests an increase in the proportion of disordered polymer [55,62], as expected at the onset of a melt, while the decreased intensity of the 0–0 shoulder may be indicative of a greater degree of interchain coupling and therefore the formation of H-aggregates [63]. Annealing at temperatures higher than the melt disrupts these aggregates, and although minor vibronic shoulders are still present, these are likely due to some degree of aggregation during the cooling prior to the measurement of the spectrum.…”

Photophysical Behaviors at Interfaces between Poly(3-Hexylthiophene) and Zinc Oxide Nanostructures

“…While only 0-1 sideband appears in the former type due to the constraint of symmetry, the transition corresponding to 0-0 sideband is strongly allowed in the latter type. Baghgar proposed a theory that such 0-0 to 0-1 sideband ratio would rise from H-to J-aggregates as the coil chain conformation of polymer becomes more prevailing compared to the rod-like chain 20) . In our study, as illustrated in Fig.…”

Efficient photoinduced charge transfer in chemically-linked organic-metal Ag-P3HT nanocomposites

“…The difference in energy between the peak and shoulder emission is ~0.18 eV and can be ascribed to stretching vibration energy of the C = C bond in the polymer [26]. H-type (face-to-face) and J-type (head-to-tail) aggregates in the regio-regular P3HT films have been proposed [27]. In H aggregate systems, 0-0 electronic transitions between the ground state and the lowest energy level of the vibronic excited state are forbidden by symmetry, giving rise to a much larger 0-1 intensity than the 0-0 sideband.…”