Efficient White‐Light Generation from Ionically Self‐Assembled Triply‐Fluorescent Organic Nanoparticles

Abstract

Low cost, simple, and environmentally friendly strategies for white-light generation which do not require rare-earth phosphors or other toxic or elementally scare species remain an essentially unmet challenge. Progress in the area of all-organic approaches is highly sought, single molecular systems remaining a particular challenge. Taking inspiration from the designer nature of ionic-liquid chemistry, we now introduce a new strategy toward white-light emission based on the facile generation of nanoparticles comprising three different fluorophores assembled in a well-defined stoichiometry purely through electrostatic interactions. The building blocks consist of the fluorophores aminopyrene, fluorescein, and rhodamine 6G which represent blue, green, and red-emitting species, respectively. Spherical nanoparticles 16(±5) nm in size were prepared which display bright white-light emission with high fluorescence quantum efficiency (26 %) and color coordinate at (0.29, 0.38) which lie in close proximity to pure white light (0.33, 0.33). It is noteworthy that this same fluorophore mixture in free solution yields only blue emission. Density functional theory calculations reveal H-bond and ground-state proton transfer mediated absolute non-parallel orientation of the constituent units which result in frustrated energy transfer, giving rise to emission from the individual centers and concomitant white-light emission.

Tuning the Förster Resonance Energy Transfer through a Self‐Assembly Approach for Efficient White‐Light Emission in an Aqueous Medium

“…The Commission Internationale de l′Eclairage (CIE) coordinates of white‐light emission were found to be x= 0.33, y= 0.36, which is close to that of the pure white (0.33, 0.33) light (Figure b). The quantum yield of WLE aqueous micellar solution was found to be as high as % (Figure S13) which is comparable or higher than that of the notable all‐organic and organic‐inorganic hybrid WLE assemblies in water reported to date such as, DP/DCM (36 %), TPDC‐Bz‐based nanoparticles (35 %) ZnO‐EC DNA (34 %), [APR6G][FL] nanoparticles (26 %), TPECVs@RhB (21 %), C‐dot‐C153‐AuNC (19 %), and Q[8]‐G1 (12 %) (Tables S5 and S6).…”

“…Supramolecular self‐assembly approaches have been found to be effective for the generation of WLE materials . Considering an environmental disposal perspective, the fabrication of WLE materials using non‐hazardous substances and eco‐friendly solvents like water has drawn significant attention . Würthner and co‐workers demonstrated FRET between biscarbazole (energy donor) loaded into the hydrophobic core of perylene bisimide micelles (energy acceptor) leading to white‐light emission .…”

“…Das et al. reported water‐dispersible nanoparticles of trifluorophoric organic salt [APR6G]FL displaying bright white‐light emission with quantum yield of 26 % …”

“…[28][29][30][31][32][33] Consideringa ne nvironmental disposal perspective,t he fabrication of WLE materials using non-hazardouss ubstances and eco-friendly solvents like water has drawnsignificant attention. [18,20,[34][35][36][37][38] Würthner and co-workersd emonstrated FRET between biscarbazole (energy donor) loadedi nto the hydrophobicc ore of perylene bisimidem icelles (energya cceptor) leading to white-light emission. [34] Das et al reported water-dispersible nanoparticles of trifluorophoric organic salt [APR6G]FL displaying bright white-light emission with quantum yield of 26 %.…”

“…[34] Das et al reported water-dispersible nanoparticles of trifluorophoric organic salt [APR6G]FL displaying bright white-light emission with quantum yield of 26 %. [36] The development of ac onvenientp rotocol for the fabrication of highq uantum efficiency WLE materials employing simple molecular systemsi na na queous mediums till remains ac hallenge. Moreover,r etaining the pure white-light emission while transferringt he organic assemblies from solution to solid substrates is acritical issue which is relevant for the device fabrication.…”