Aggregation-Induced Emission and White Luminescence from a Combination of π‑Conjugated Donor–Acceptor Organic Luminogens

Two new star-shaped
phenyl- and triazine-core based donor–acceptor (D–A)
type conjugated molecules bearing triphenylamine end-capped arms were
synthesized and characterized as imminent organic optoelectronic materials.
Photophysical properties of the compounds were explored systematically
via spectroscopic and theoretical methods. Because of the presence
of donor–acceptor interactions, these luminogens display multifunctional
properties, for instance, high extinction coefficient, large stokes
shift, and pronounced solvatochromic effect. The compounds also exhibited
phenomenon known as aggregation-induced emission on formation of nano-aggregates
in the tetrahydrofuran–water mixture. The aggregate formation
was confirmed by transmission electron microscopy, scanning electron
microscopy, and dynamic light scattering analyses. Moreover, by controlling
the electron withdrawing ability of the acceptor, complementary emissive
fluorophores (blue and yellow) were achieved. These two complementary
colors together span the entire range of visible spectrum (400–800
nm) and therefore when mixed in a requisite proportion generate white
light in solution phase. These findings have potential for the progress
of new organic white light radiating materials for applications in
lighting and display devices.