Y2Si4N6C:Ce3+ carbidonitride green-yellow phosphors: novel synthesis, photoluminescence properties, and applications

Abstract

The Y₂Si₄N₆C:Ce³⁺ carbidonitride phosphor has been successfully synthesized via a novel acid-driven carbonization and carbothermal reduction nitridation method (ADC–CRN). This novel approach for Y₂Si₄N₆C:Ce³⁺ promises lower heating temperature and shorter heating time than classical methods, indicative of a cost-effective and facile way to search for new silicon-based carbidonitrides. In contrast to Ce³⁺ activated (oxy)nitrides showing blue-green emissions, Y₂Si₄N₆C:Ce³⁺ exhibits an individual green-yellowish emission band centered at 550 nm which is ascribed to the incorporation of highly covalent C⁴⁻ into the host lattice. The sp³ hybrid C⁴⁻ was identified through high resolution electron energy loss spectroscopy analysis (EELS). Direct evidence for sole substitution of Ce³⁺ for Y³⁺ in Y₂Si₄N₆C is represented for the first time using electron paramagnetic resonance (EPR) spectra. The red shift induced by the increasing Ce³⁺ content in Y₂Si₄N₆C is reasonably deduced by the energy transfer model of intra-Ce³⁺ and inter-Ce³⁺ ions. A pc-w-LED packaging was fabricated via a combination of the yellow Y₂Si₄N₆C:Ce³⁺ and blue La₂Si₄N₆C:Ce³⁺ phosphors prepared using a 365 nm n-UV chip. The w-LED device shows a good color rendering index (R_a), CIE chromaticity coordinates and correlated color temperature (CCT) of 83.8, (0.3258, 0.3314) and 5819 K, respectively. These results suggest that Y₂Si₄N₆C:Ce³⁺ has great potential for use in UV-LED-driven white emitting diodes.