The pathways and dynamics of converting spin-allowed (S = 0) singlet excitons to spin-forbidden 1) triplets have significant implications in determining performance metrics conjugated polymers optoelectronic devices. We study the effect structural ordering factors on triplet formation self-assembled aggregate π-stacked chains poly(3-hexylthiophene) (P3HT) using single-molecule time-resolved intensity modulation electric-field-dependent photoluminescence (PL) spectroscopy. Triplet generation...

Triplet formation and interactions with emissive singlet excitons are investigated in poly(3-hexylselenophene) (P3HS) using single molecule spectroscopy. P3HS is a heavy atom analog of the more commonly studied poly(3-hexylthiophene) (P3HT), benchmark polymer for solar cells. tends to aggregate strongly which necessitates dilution ultra-low levels within solid inert host order resolve photophysical responses chains. Fluorescence excitation intensity modulation performed on isolated chains...

We demonstrate long-lived, multi-mode vibrational dynamics in a class of non-emissive conjugated polymers believed to undergo singlet fission.

Effective charge transfer (CT) doping of conjugated polymers depends on electronic and structural factors alike, though the former receives most attention in design mechanistic considerations. We investigate CT chalcogenophene-vinylene with similar frontier orbital energies packing characteristics as other semicrystalline polythiophenes frequently used studies, for example, poly(3-hexylthiophene), or P3HT. However, unlike P3HT, these systems experience large vibrational displacements along...

Fluorophores experience altered emission lifetimes when incorporated into and liberated from macromolecules or molecular aggregates; this trend suggests the potential for a fluorescent, responsive probe capable of undergoing self-assembly aggregation consequently altering lifetime its fluorescent moiety to provide contrast between active inactive probes. We developed cyanobenzothioazole-fluorescein conjugate (1), spectroscopically examined changes caused by reduction-induced in vitro. A...

We investigate the effect of molecular geometry and conformational flexibility on electronic coupling charge transfer interactions within propeller-shaped perylene diimide (PDI) tetramer arrays differing by number covalent linkages to a central spirobifluorene core. Electronic spectra tetramers with one ("floppy") or two ("rigid") bay display evidence character in either ground excited states. Floppy exhibit marked red-shifted broadened absorption features that we assign as overlapping...

Intersystem crossing in conjugated organic molecules is most conveniently viewed from pure electronic perspectives; yet, vibrational displacements may often drive these transitions. We investigate an alkyl-substituted thienylene–vinylene dimer (dTV) displaying efficient triplet formation. Steady-state and Raman spectra display large Stokes shifts (∼4000 cm–1) involving high-frequency skeletal symmetric stretching modes (∼900–1600 addition to of low-frequency torsional motions (∼300–340...

Spin-forbidden triplet excited states of conjugated polymers have important ramifications for material performance and stability, yet processes are difficult to understand control at the bulk level. We investigate effect a heavy heteroatom chain conformation on triplet-mediated oxygen photochemistry events in poly(3-hexylthiophene) (P3HT) poly(3-hexylselenophene) (P3HS) systems using high throughput single molecule spectroscopic imaging. Fluorescence intensity transients both exhibit...

Abstract The advent of multiple exciton harvesting schemes and prolonging lifetimes to improve performance attributes solar cells based on conjugated organic materials presents some interesting challenges that must be overcome in order realize the full potential these strategies. This is especially important for applications involving multi-chromophoric polymers where interactions between spin-forbidden triplet excitons can significant are mediated by chain conformation. We use single...

Resolving the population dynamics of multiple triplet excitons on time scales comparable to their lifetimes is a key challenge for multiexciton harvesting strategies, such as singlet fission. We show that this information can be obtained from fluorescence quenching and stochastic kinetic modeling simulations single nanoparticles comprising self-assembled aggregated chains poly(3-hexylthiophene) (P3HT). These multichromophoric structures exhibit elusive J-aggregate type excitonic coupling...

The formation of long-lived triplet excited electronic states has important ramifications for conjugated organic materials used in optoelectronic devices. In the case polymers, unravelling various structural factors mediating processes is difficult because heterogeneity effects due to intrinsic molecular weight polydispersity and large conformational degrees freedom. Conformation-dependent coupling between chromophore segments also modulates relaxation branching ratios that may vary...

Fluorophores are greatly influenced by their environment. In full paper, L. Cui et al. show that triggering the aggregation of a self-condensing scaffold labeled with fluorophore induces changes in emission spectrum, polarization, and lifetime. The aggregates exhibited shorter lifetime detectable cells fluorescence imaging microscopy, thus suggesting triggered strategies can be used probes for various biological events through imaging.

Abstract Fluorophores experience altered emission lifetimes when incorporated into and liberated from macromolecules or molecular aggregates; this trend suggests the potential for a fluorescent, responsive probe capable of undergoing self-assembly aggregation consequently altering lifetime its fluorescent moiety to provide contrast between active inactive probes. We developed cyanobenzothioazole-fluorescein conjugate ( 1 ), spectroscopically examined changes caused by reduction-induced in...