2 research outputs found
Versatile Luminescent Europium(III)−β-Diketonate-imidazo-bipyridyl Complexes Intended for White LEDs: A Detailed Photophysical and Theoretical Study
Three
ancillary ligands based on imidazo-bipyridyl with phenyl (Ph), naphthyl
(Np), and triphenylamine (TPA) substitution were synthesized and secondhand
to formulate the consistent europiumÂ(III) ternary complexes using
thenoylÂtrifluoroÂacetone as an anionic ligand. The complete
investigation of spectroscopic, photophysical, and electrochemical
properties was carried out. The attained results for all the ancillary
ligands and their corresponding Eu complexes were compared with one
another. All the Eu complexes reveal a broad excitation band ranging
from the near-UV to blue region, along with high intense emission
and apposite color purity. To further understand the ligand-to-metal
energy transfer (ET) process, the geometry of the ligand was optimized
and the energy level location (singlet and triplet) was calculated
by using DFT and TD-DFT calculations. On the basis of the theoretical
calculation, the ET mechanism was proposed. From PL emission spectra
in the solid state, complete ET occurs from Ph, Np based ancillary
ligands to the Eu<sup>3+</sup> ion, which yields a pure red emission,
whereas the TPA functionalized based Eu complex shows incomplete ET.
Fortunately, white emission was observed in the TPA based Eu complex
in the solid state. The white LED was fabricated by using a white
emitting complex integrated with 395 nm emitted LED (InGaN) chips
under 20 mA forward-bias current. The excitation source from LED was
fully observed by the complex shown for 3Eu and showed yellowish emission
in different concentrations (the similar observation also reflected
in solid). However, in the case of 1Eu and 2Eu complexes, they showed close
to white emission. The Commission International de I’Eclairage
(CIE) chromaticity coordinates are close to the National Television
Standard Committee standard value for white emission, and in addition,
the complex 3Eu coated with the blue LED chip (460 nm) by PMMA (1:10)
showed bright white emission with CIE <i>x</i>, <i>y</i> values of 0.30, 0.33, respectively
Controlled Energy Transfer from a Ligand to an Eu<sup>III</sup> Ion: A Unique Strategy To Obtain Bright-White-Light Emission and Its Versatile Applications
A new
diphenylamine-functionalized ancillary-ligand-coordinated europiumÂ(III)
β-diketonate complex showed incomplete photoexcitation energy
transfer from a ligand to a Eu<sup>III</sup> ion. A solvatochromism
study led to a balancing of the primary colors to obtain single-molecule
white-light emission. Thermal-sensing analysis of the europium complex
was executed. The europium complex, conjugated with a near-UV-light-emitting
diode (395 nm), showed appropriate white-light-emission CIE color
coordinates (<i>x</i> = 0.34 and <i>y</i> = 0.33)
with a 5152 K correlated color temperature