RESUMO

Narrow band red-emitting phosphors based on organo-Eu(III) complexes prove their energetic features with surprising performance in smart red/white LEDs, sensing, and biological fields. In this report, a series of unique Eu(III) complexes have been synthesized with coumarin integrated with a class of phenanthroline(Phen)/thiabendazole(TBZ) based ancillary ligands and dibenzoyl methane (DBM)/2-theonyl trifluoroacetone (TTA) as an anionic ligand. The computational study reveals that the TBZ/Phen-based neutral ligands are superior energy harvesters to those other reported analogue neutral ligands. All the Eu-complexes demonstrated outstanding red emission due to electric dipole (ED) transition (5D0 → 7F2) in solid, solution, and thin film with high quantum yield (QY). Theoretical analysis (TD-DFT) and experimental findings describe that the energy transfer (ET) from the ligand's triplet level to the Eu(III) ion is completely occurring. The Eu(III) complexes can potentially be used to fabricate intense hybrid white and red LEDs. All of the fabricated red LEDs revealed high luminous efficiency of radiation (LER) values. The fabricated blue LED based hybrid white LEDs displayed remarkable performance with a low correlated color temperature (5634 K), high color rendering index 88%, and CIE values (x = 0.33; y = 0.342) for 3Eu. By interaction with acid-base vapors, Eu-complexes displayed effectively alterable on-off-on luminescence. Further, cellular imaging shows that Eu-complexes can be a potential biomarker for cancer cell lines.

Assuntos

Cumarínicos , Európio , Teste de Materiais , Fenantrolinas , Európio/química , Cumarínicos/química , Humanos , Fenantrolinas/química , Estrutura Molecular , Materiais Biocompatíveis/química , Materiais Biocompatíveis/síntese química , Tamanho da Partícula , Imagem Óptica , Complexos de Coordenação/química , Complexos de Coordenação/síntese química , Medições Luminescentes , Substâncias Luminescentes/química , Substâncias Luminescentes/síntese química

RESUMO

In pursuit of enhancing white light quality for solid-state lighting (SSL) applications, an attempt has been made to design novel imidazo-bipyridyl ligands as an ancillary ligand to obtain multiple emissions (mimic sunlight) in the Eu-complex. By strategically modifying the phenanthroline core with imidazo-bipyridyl incorporation with 1 or 2-Napthyl groups at the C1 position, the excitation spectral line is successfully shifted from Ultraviolet (UV) to near UV/visible spectrum (where the LED emission occurs). The ligands showed greenish blue emission in solid and solution. Density Functional Theory (DFT) calculations were utilized to understand the energy transfer processes from ligand to Eu ion in the Eu complexes. The analysis revealed that the energy transfer is incomplete, primarily attributed to the proximity of triplet state energy levels to the resonance level of Eu(III) ions as reflected in solvatochromism. These complexes exhibit a unique dual emissive behavior (emitting multi-color) including white light across various solvents. These complexes hold great promise as single-component white light-emissive materials, with potential applications in white light-emitting diodes (WLED). The fabricated white LED showed an excellent color rendering index (CRI ~93 %). Beyond lighting, this distinctive property opens avenues for temperature sensing ([Eu(DBM)31-Naph] shows the highest sensitivity of Sr=10.97 %, and [Eu(DBM)32-Naph] shows the highest sensitivity of Sr=5.5 % at 333 K) and vapoluminescent (acid-base on-off-on luminescence) studies. This research pioneers the development of these complexes as potential single-component materials for superior white LEDs, underlining their multifaceted utility in cutting-edge lighting and sensing technologies.

RESUMO

Narrow band red-emitting phosphors are significant constituents but still a bottleneck for next-generation smart displays and high-performance lighting (solid-state lighting based white light-emitting diodes (WLEDs)) technology. This review emphasizes the fundamental understanding and comprehensive overview of the recent progress and challenges associated with inorganic phosphors or down (wavelength) convertors, providing special attention to narrowband red-emitting oxide phosphors for phosphor-converted WLEDs (pc-WLEDs). In this context, the comprehensive progress on trivalent europium (Eu3+, in scheelite and double perovskite structures) based oxide phosphors with special emphasis on structure-composition-property-correlations is briefly reviewed. Furthermore, the challenges faced in the design of new oxide red phosphors and strategies to improve their absorption, emission efficiency, and future research direction are highlighted.