Emission Color Tuning and White Light Generation from
a Trimolecular Cocktail in Cationic Micellar System with Promising
Applicability in the Anticounterfeiting Technology
Version 2 2021-06-17, 13:05Version 2 2021-06-17, 13:05
Version 1 2021-06-15, 14:12Version 1 2021-06-15, 14:12
journal contribution
posted on 2021-06-17, 13:05authored byFirdaus
Ahmad Ahanger, Nighat Nazir, Mohd Sajid Lone, Saima Afzal, Aijaz Ahmad Dar
The
development of photoluminescent (PL) systems, displaying multiple
stimuli-responsive emission color tuning, has been the pressing priority
in the recent times due to their huge role in contemporary lighting
and anticounterfeiting technologies. Acknowledging this importance,
we present a simple and eco-friendly PL system showing emission color
tuning in response to different stimuli, that is, the composition
of the system, pH, excitation wavelength, and the temperature with
the plus point of getting significantly pure white light emission
(WLE). The novel system is fabricated from the aqueous mixture of
three organic fluorophores, umbelliferone (UMB), fluorescein
(FLU), and Rhodamine-B (RB). By varying
the fluorophore composition in the mixture at pH 12, nearly pure WLE
with a Commission Internationale d’Eclairage (CIE) 1931 profile
of (0.33, 0.33) was obtained at the excitation wavelength of 365 nm,
the sustainability of which was ensured by employing the micellar
self-assemblies of tetradecyltrimethylammonium bromide (TTAB) molecules. Similar WLE was obtained under mildly acidic conditions
(pH 6) but at the excitation wavelength of 330 nm. By proper tuning
of pH and the wavelengths of the system to use it as a fluorescent
ink, we found a remarkable and highly applicable phenomenon observed
for the first time, that is, triple-mode orthogonal emission color
tuning with white light ON/OFF switching. We validate the vital applicability
of this phenomenon in protecting the authenticity of the document
with its hard-to-counterfeit property. The applicability of this phenomenon
is also explored by synthesizing PVA-based fluorescent films from
the tri-fluorophore mixture. Moreover, the emission color of the PL
system was explored lucidly for its temperature dependence owing to
the thermal responsiveness of RB emission, where the
PL system proves to be a full-color RGB system.