Hot-exciton harvesting via through-space single-molecule based white-light emission and optical waveguides. Issue 31 (18th July 2022)

• Record Type: Journal Article
• Authors: Barman, Debasish; Annadhasan, Mari; Chandrasekar, Rajadurai; Iyer, Parameswar Krishnan
• Is Part Of: Chemical science. Volume 13:Issue 31(2022)
• Page Start: 9004
• Page End: 9015
• Publication Date: 2022-07-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2sc02172b
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Through-space donor–alkyl bridge–acceptor multifunctional organic single molecules that simultaneously displayed white light emission, thermally activated delayed fluorescence, room temperature dual phosphorescence and optical wave-guiding properties. Abstract : Through-space donor–alkyl bridge–acceptor (D–σ–A) luminogens are developed as new organic single-molecule white light emitters (OSMWLEs) involving multiple higher lying singlet (S n ) and triplet (T m ) states (hot-excitons). Experimental and theoretical results confirm the origin of white light emission due to the co-existence of prompt fluorescence from locally excited states, thermally activated delayed fluorescence (TADF), and fast/slow dual phosphorescence color mixing simultaneously. Notably, the fast phosphorescence was observed due to trace amounts of isomeric impurities from commercial carbazole, while H-/J-aggregation resulted in slow phosphorescence. Crystal structure-packing-property analysis revealed that the alkyl chain length induced supramolecular self-assembly greatly influenced the solid-state optical properties. Remarkably, the 1D-microrod crystals of OSMWLEs demonstrated the first examples of triplet harvesting waveguides by self-guiding the generated phosphorescence through light propagation along their longitudinal axis. This work thus highlights an uncommon design strategy to achieve multi-functional OSMWLEs with in-depth mechanistic insights and optical waveguiding applications making them a potentially new class of white emissive materials.