Enhanced Luminescence from Emissive Defects in Aggregated Conjugated Polymers

Abstract

Degradation experiments and model studies suggested that the longer lived green fluorescence from an aggregated poly(p-phenylene ethynylene) (PPE) was due to the presence of highly emissive, lowenergy, anthryl defect sites rather than the emissive conjugated polymer excimers proposed in a previous report. After elucidating the origin of the green fluorescence, additional anthryl units were purposely incorporated into the polymer to enhance the blue-to-green fluorescence color change that accompanied polymer aggregation. The improved color contrast from this anthryl-doped conjugated polymer led to the development of crude solution-state and solid-state sensors, which, upon exposure to water, exhibited a visually noticeable blue-to-green fluorescence color change.

Fabrication of Supramolecular Semiconductor Block Copolymers by Ring‐Opening Metathesis Polymerization

“…In contrast, the metallosupramolecular BCP exhibits a large hypsochromic shift and an enhanced emission. We attribute the former behavior to the supramolecular linkers disrupting π‐conjugation16 and suggest the latter behavior results from a controlled self‐assembly that prevents the formation of large aggregates. The stark contrast between the emergent properties of the hydrogen‐bonded BCP and the metallosupramolecular BCP are attributed to the ability of the metal center to facilitate through‐bond interchromophore communication upon self‐assembly 13a,b…”

Time-resolved photoluminescence study of low-energy emission mechanisms in oligofluorene and polyfluorene films

“…However, the difficulty of preparing chemically pure materials devoid of chemical defects, such as fluorenone, and the inevitable polydispersity of chain lengths make the extensive experimental studies on polyfluorenes subject to serious uncertainties. This is because the emission properties are significantly influenced by the presence of residual emission quenchers and the morphology-dependent intraand intermolecular energy transfer processes [18][19][20][21].…”

Oligonucleotide‐mediated aggregation of a cationic conjugated polymer for fluorescent detection of mercury ions in an aqueous medium

“…A further increase in the concentration to 5.44 × 10 −5 M in aqueous solution, facilitates larger increase in longer emission bands (green) at 535 nm, compared to the lower emission band, and moreover, only longer the emission wavelength is observed in the solid state, which corresponds to an emission band of BT segments. This phenomenon can be understood by intramolecular and intermolecular exciton migration in aqueous solution and in the aggregated state, respectively, which is described in published literature . (a), To gain an insight into the aggregation‐induced fluorescence color change of P2 , ethanol was added into an aqueous solution of P2 , in which P2 showed better solubility than in water.…”

“…In a dilute, well‐dissolved ionic conjugated polymer solution, exciton transport can be approximated by a one‐dimensional (1D) random walk within an isolated polymer chain. However, interchain exciton migration and a 3D random walk become possible if the polymers aggregate within close proximity to each other …”