Photoswitching and Thermoresponsive Properties of Conjugated Multi‐chromophore Nanostructured Materials

Abstract

Conjugated multi-chromophore organic nanostructured materials have recently emerged as a new class of functional materials for developing efficient light-harvesting, photosensitization, photocatalysis, and sensor devices because of their unique photophysical and photochemical properties. Here, we demonstrate the formation of various nanostructures (fibers and flakes) related to the molecular arrangement (H-aggregation) of quaterthiophene (QTH) molecules and their influence on the photophysical properties. XRD studies confirm that the fiber structure consists of >95% crystalline material, whereas the flake structure is almost completely amorphous and the microstrain in flake-shaped QTH is significantly higher than that of QTH in solution. The influence of the aggregation of the QTH molecules on their photoswitching and thermoresponsive photoluminescence properties is revealed. Time-resolved anisotropic studies further unveil the relaxation dynamics and restricted chromophore properties of the self-assembled nano/microstructured morphologies. Further investigations should pave the way for the future development of organic electronics, photovoltaics, and light-harvesting systems based on π-conjugated multi-chromophore organic nanostructured materials.

Perspective of dye-encapsulated conjugated polymer nanoparticles for potential applications

“…suitable because they have indirect excitons, which increase the excited state lifetime, and excitation in H-aggregates leads to production of delocalized singlet excitons at room temperature [52,53]. Furthermore, extent of H-aggregation in quarterthiophene (QTH) is controlled by changing the solvent polarity [54]. With increasing solvent polarity, the morphology of the aggregated nanostructure is changed from fibre to flake with decreasing crystallinity.…”

Photon Harvesting in Conjugated Polymer-Based Functional Nanoparticles

“…(C) Schematic representation of reversible transformation of QTH fiber and flakes nanostructures, and (D) Decay curves of QTH in THF (a), QTH fiber (b) and QTH flakes (c). Adapted with permission from ref . Copyright 2015 John Wiley & Sons, Inc.…”

“…A strong intermolecular π- electronic coupling occurs in the J -aggregation, which enhances the coherent electronic delocalization . Again, H-aggregated fiber and flake nanostructures of quaterthiophene (QTH) molecules with changing solvent polarity have demonstrated photon harvesting applications . Structural analysis reveals that fiber structure is crystalline in nature, whereas flake structure is found to be amorphous.…”

“…63 Again, H-aggregated fiber and flake nanostructures of quaterthiophene (QTH) molecules with changing solvent polarity have demonstrated photon harvesting applications. 64 Structural analysis reveals that fiber structure is crystalline in nature, whereas flake structure is found to be amorphous. Spectroscopic investigations reveal that the nature of aggregation has an impact on photoswitching, thermoresponsive photoluminescence properties, and the relaxation dynamics of the self-assembled structures; such knowledge is beneficial for developing of organic electronics.…”

The Impact of Aggregation of Quaterthiophenes on the Excited State Dynamics

“…Oligomers of thiophene are exciting candidates for field-effect transistors, solar cells, and light-emitting diodes due to their extensive π-electron delocalization along the π-conjugated backbone. − These π-conjugated oligomers possess well-defined functional properties. They form highly ordered self-assembled organic nanostructures, showing photoswitching and thermoresponsive behavior. ,− Muccini and co-workers have demonstrated the supramolecular organization of α-sexithiophene on a silicon-based transistor gate dielectric surface . Bard and co-workers reported electro-chemiluminescence properties of oligothiophene-based nanostructures .…”