Rare earth ions elemental nanoparticles based silica composites for solid state lighting applications

Abstract

Solid state luminescent materials have garnered considerable attention for the past several years due to their significant role in various fields like optoelectronic devices, sensors, data storage and light emitting applications. The thesis entitled “Rare-Earth Ions/Elemental Nanoparticles Based Silica Composites for Solid State Lighting Applications” describes synthesis and optical investigations on different rare earth (RE) ions/elemental nanoparticles (EN) doped silica composites for solid lighting applications. Discrete sharp green-red luminescence of RE ions (Tb3+, Eu3+) are combined with blue emission of carbon quantum dots (CQDs) to achieve WLE materials with warm to cool tunable correlated color temperatures (CCTs). Obtained composites show a continuous tuning from warm to cool white emission with adjustable CCTs (3508 to 6114 K) under excitation wavelength of 393 nm. Additionally, eco-friendly, biomass derived single component carbon nanoparticles with dual emission bands are synthesized to develop tunable WLE materials. Upon change in the excitation wavelengths from 410 nm to 370 nm, white light emissions are obtained with tunable CCT values from 2648 K to 8980 K respectively. On the other hand, Se- Tb3+ doped silica and CQDs-Tb3+ doped silica is investigated for its potential in achieving solid state lighting systems. Apart from this, phase dependent optical behaviour for Se-Tb3+ doped silica is systematically analyzed for its applications as optical amplifier and optical attenuator. For CQDs- Tb3+ doped silica, colour tuning is achieved with a transition from blue (0.1952, 0.2328) to near white (0.2201, 0.3106). Furthermore, nanocarbon doped silica are studied for their tunable structural and optical properties. In accordance with the increase of carbon content in silica, a graphitic to non- graphitic crystalline transitions with a concentration mediated spectral broadening is obtained. Non-graphitic carbon nanoparticles with wide emissions yielded cool white CCTs (˃ 6000 K) and good CRI value (~80) with favorable CIE coordinates.