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Abstract The common flower Clitoria ternatea is gifted with organic dyes anthocyanin delphinidin and betalains betacyanin that exhibit broad emission peaks centered at 490 nm and 630 nm. These fresh emission bands in the blue-green and red regions make it a potential white light source that can swap the conventional rare-earth doped phosphor materials. By this line, the extract shows decent emission in its solution state. However, the emission intensity reduces rapidly after a while, owing to the high decay rate of organic dyes in their pure form. Thus, the floral extract is combined with the antioxidant La2O3, reducing the luminescence decay to a noticeable value. The complex formation does not alter the innate La2O3 crystal structure, identified by the XRD peaks, but aids with near-white emission. Upon complex formation, the optical band gap of the host La2O3 falls to the semiconductor range, from 5.1 eV to 2.5 eV. White light emission from La2O3: Clitoria ternatea complex is studied for different extract concentrations and heating conditions, and deemed as a potential replacement for conventional rare-earth doping.

The present study deals with the synthesis and characterization of the Gd2O3:Eu3+ nanophosphors and the impact of Y3+ co-doping on the structural and optical properties of the Gd2O3:Eu3+. All nanophosphors are synthesised by facile low temperature solution combustion method using citric acid as a chelating agent. The XRD pattern of as-synthesised Gd2O3:Eu3+ confirmed the presence of mixed-phase crystallites and upon annealing, it transforms to a cubic phase. The images of TEM and FE-SEM confirm that the samples are spherical after annealing. From the perspective of the emission spectra of Gd2O3:Eu3+, the 5D0 to 7F2 (613 nm) optical transition is the most important among the different narrow emission peaks observed in the visible region. Optimal doping concentration of Eu3+ was 7 wt%. Y3+ ions were incorporated into this Gd2O3:7 wt%Eu3+ nanophosphors. Y3+ co-activated samples crystallized in the cubic structure and exhibited a threefold enhancement in emission intensity and considerable improvement in lifetime and quantum efficiency compared to Gd2O3:Eu3+ nanophosphors. Temperature-dependent PL spectra indicate that the obtained nanophosphor exhibits excellent thermal stability and the activation energy was observed to be 0.4773 eV. Beyond that, red CIE coordinates, with excellent colour purity (greater than 95%) and suitable colour-correlated temperature (below 5000 K) suggest that the prepared red-emitting nanophosphors have immense potential in phosphor converted LED (pc-LED) applications. [ABSTRACT FROM AUTHOR]

Numerous structural and conductive properties of barium cerate (BC) make this material a promising candidate for energy storage applications. In this work, we demonstrated that BC can be proficiently functionalized by incorporating trivalent samarium ions to give rise to optical properties. Single-phased BaCeO 3 :Sm 3+ (BCS) phosphors were synthesized by gel combustion technique followed by calcination. The crystal structure, optical properties, and prospective applications in LEDs were investigated systematically. By linking the information acquired from the diffuse reflectance spectra with that of the PL spectra, we better understood the electronic level structure and energy transfer mechanism. Fine yellow-orange luminescence with 100% color purity (CP) and lower Correlated Color Temperature (CCT) has been achieved via energization at 348 nm wavelength. The x = 0.02 Sm 3+ has been identified as the optimized content for the luminescence with a quantum efficiency of 34.2%. Obtained yellow-orange coordinates (0.564, 0.435) are proximate to commercialized L3 rank amber LED (Nichia corporation). The present results signify that UV light can suitably energize the BCS phosphor to get monochromatic amber light which can be used to guard medications during manufacture and storage., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)