Broad-band Emissive Phenanthroimidazole-based Donor-Acceptor Luminogens for Hybrid White Light Emitting Diodes and Sensors for Picric acid detection

Abstract

In this article, a series of phenanthroimidazole based donor-acceptor luminogens have been designed and synthesized whose design rationale, molecular structure, and spectroscopic characterization will be detailed to provide a comprehensive understanding of various applications integrating hybrid white LED fabrication and sensing properties (both temperature sensing and picric acid detection). We validate our findings through electrochemical analysis, supported by DFT calculations, including the determination of HOMO-LUMO gap via cyclic voltammetry and all the fluorophores are characterised by single crystal XRD. Among the designed fluorophores, PhAn takes the lead in white LED technology. This fluorophore was fabricated on a soft UV LED chip with a precise PMMA: organic fluorophores and Eu complex mass ratio, the resulting hybrid white LED boasts an impressive CRI of 83 % and CIE values of 0.29, 0.31, with a correlated color temperature of 9433 K. This accomplishment is further underscored by a luminous efficacy of radiation (LER) at 288 lm W-1, solidifying PhAn role as a key contributor to efficient and visually appealing white light emission. Moreover, the integration of organic fluorophores on near UV chips enhances their practical application. White light has been generated by physical mixing of fluorophores by integrating with Eu(III) phosphor in equimolar ratio offering a dual solution to both efficient white LED fabrication and advanced detection methods for hazardous materials. Additionally, the designed fluorophores revealed a stern-volmer quenching constant of 9.09 x 10-2 M-1 and a detection limit of 3.46 ppb which has shown the ability to detect picric acid using fluorescence, DFT analysis, and 1H NMR spectroscopy and a thorough study of a single crystal of all the synthesized fluorophores has been discussed.