Controlling of Structural Ordering and Rigidity of β-SiAION:Eu through Chemical Cosubstitution to Approach Narrow-Band Emission for Light-Emitting Diodes Application

Narrow-band greem-emitting phosphor beta-SiA-lON:Eu has been widely used in advanced wide-gamut backlighting devices. However, the origins for unusual sharp lines in photoluminescence emission at room temperature and tunable narrow-band-emission tailored by reducing Al-O in beta-SiAlON:Eu are still unclear. Here, the presence of sharp-line fine structure in the emission spectra of beta-SiAlON:Eu is mainly due to purely electronic transitions (zero phonon lines), and their vibronic repetitions resulting from the multimicroenvironment around Eu2+ ions that has been revealed by relative emission intensity of sharp line depends on excitation wavelength and monotonously increasing decay time. The specific features of the Eu2+ occupying interstitial sites indicate that the effect of crystal field strength can be neglected. Therefore, the enhanced rigidity and higher ordering structure of beta-SiAlON:Eu with decreasing the substitution of Si-N by Al-O become the main factors in decreasing electron lattice coupling and reducing inhomogeneous broadening, favoring the blue shift and narrow of the emission band, the enhanced thermal stability, as well as the charge state of Eu2+. Our results provide new insights for explaining the reason for narrow-band-emission in beta-SiAlON:Eu, which will deliver an impetus for the exploration of phosphors with narrow band and ordering structure.