(Invited) Discovery and Structural Design of New LEDs Phosphors

Phosphor materials enable the wavelength conversion to realize the full-color white emission light-emitting diodes (LEDs). So far much effort has been devoted to the design and discovery of novel LED phosphors for solid state lighting. Understanding and exploring the structural design principles of the inorganic hosts are necessary for the discovery of novel LED phosphors. Our recent work focuses on the discovery of new phosphor materials based on the structural evolution and the crystallographci sites engineering. Firstly, photoluminescence tuning can be realized via the cation substitution on one site, and hereby we have discovered several types of M2SiO4-based and M3(PO4)2-based phosphors with tunable emission for white LEDs.1-2 Secondly, we have recently proposed the concept of “chemical unit cosubstitution” as one potential design scheme, and the chemical unit cosubstitution strategy is applied to the melilite structure class designing the Ca2(Al1−x Mg x )(Al1−x Si1+x )O7:Eu2+ solid solution phosphor via the [Mg2+−Si4+] for [Al3+−Al3+] cosubstitution.3 We also design the La5Si3O12N phase from La5Si2BO13 via the [B3+−O2−] by the [Si4+−N3−] cosubstitution.4 Thirdly, we have proposed a new insight into the design of the isostructural phases via the filling of M+ in the void channels of the Mg2Al4Si5O18 phase, so that the charge balance can be kept while the chemical composition varied, and this strategy will be also efficient in other porous inorganic hosts.5 Finally, we have recently studied the NaScSi2O6-based phosphor from CaMgSi2O6-based phosphor via the chemical unit cosubstitution of [Na+–Sc3+] for [Ca2+-Mg2+] unit.6 Further studies show that the isostructural solid-solution of (CaMg) x (NaSc)1-x Si2O6 (0 < x < 1) can be formed, in which cation nanosegregation enables the presence of dilute Eu2+ at two centers and their intensities are linearly proportional to x, so that it represents a new cation nanosegregation tuning of photoluminescence for the exploration of color-tunable phosphor for white LEDs.7-8 References [1] Z. G. Xia*, et. al., Inorganic Chemistry, 2015, 54, 7684-7691. (Cover paper) [2] Z. G. Xia*, et. al., Journal of Physical Chemistry C, 2015, 119, 2038–2045. [3] Z. G. Xia*, et. al., Journal of the American Chemical Society, 2015, 137, 12494-12497. [4] Z. G. Xia*, et. al., Journal of Physical Chemistry C, 2015, 119, 9488–9495. [5] Z. G. Xia*, et. al., Scientific Reports, 2015, 5, 12149. [6] Z. G. Xia*, et. al., Journal of Physical Chemistry C, 2013, 117, 20847−20854. (Cover Paper) [7] Z. G. Xia*, et. al., Scientific Reports, 2013, 3, 3310-3310-7. [8] Z. G. Xia*, et. al. Journal of the American Chemical Society, 2016, 138, 1158-1161.