Ca5La5(SiO4)3(PO4)3O2:Ce3+,Mn2+: A Color-Tunable Phosphor with Efficient Energy Transfer for White-Light-Emitting Diodes

Abstract

A series of single-composition color-tunable phosphors Ca 5 La 5 (SiO 4 ) 3 (PO 4 ) 3 O 2 : Ce 3þ ,Mn 2þ (CLSPO:Ce 3þ ,Mn 2þ ) are synthesized by solid-state reaction, and their luminescence properties are investigated. The obtained phosphors exhibit high absorption and strong excitation bands in the wavelength range of 260-400 nm, matching well with the dominant emission band of a UV lightemitting-diode (LED) chip. The energy transfer from Ce 3þ to Mn 2þ ions in CLSPO:Ce 3þ ,Mn 2þ has been studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism based on the decay lifetime data. The energy transfer efficiency as well as the critical distance are also estimated. Moreover, the phosphors can generate lights from blue through white and eventually to red by properly tuning the relative ratio of the Ce 3þ to Mn 2þ ions grounded on the principle of energy transfer. Preliminary studies show that CLSPO:Ce 3þ ,Mn 2þ can be a promising candidate for a single-phased color-tunable phosphor applied in a UV white-light LED.

Synthesis and site-selective photoluminescence property of Ca8La2(PO4)6O2: Ce3+

“…(2) Ce 3+ experience a smaller environment when Ce 3+ occupy Ca 2+ sites in Ca 8 La 2 (PO 4 ) 6 O 2 than occupying La 3+ in Ca 5 La 5 (SiO 4 ) 3 (PO 4 ) 3 O 2 :Ce 3+ and the distance between adjacent Ce 3+ will be shorter, also leading to lower concentration quenching. The photoluminescence results are in agreement with our investigation in Ca 5 La 5 (SiO 4 ) 3 (PO 4 ) 3 O 2 , that is, when Ce 3+ occupy Ca(II) sites (Ca 2+ with 7-coordination and C S symmetry), they will give a green emission rather than a blue emission [12]. The PL spectra also support the above analysis.…”

“…We think it is because when the contents of Ce 3+ are lower, it will mainly occupying Ca(I) and La(II) sites and give a violet-blue emission. With the increase of Ce 3+ contents, more Ce 3+ occupy Ca(II) sites and give a green emission [12], so the intensity of the green emission band becomes stronger compared with the blue emission band, causing the remarkable red shift of the PL spectra. Comparing figure 3a, 3b and 3c, different emission positions are obtained upon different excitation, which can be attributed to the selective excitation related to different sites.…”

“…What's more, the position of the lowest 5d band of Ce 3+ ions is strongly influenced by host lattice selection, thus the emission color can be adjusted from ultraviolet to yellow [9]. However, the potential applications of the Ce 3+ doped apatite phosphors are still limited because the emission often locates at shorter wavelength, as reported for Mg 2 Y 8 (SiO 4 ) 6 O 2 : Ce 3+ (395 nm) [10], Ca 5 (PO 4 ) 3 F: Ce 3+ (432 nm) [11] and Ca 5 La 5 (SiO 4 ) 3 (PO 4 ) 3 O 2 : Ce 3+ (385 nm) [12], etc. Till now, there has been few reports and study on the Ce 3+ -doped apatite phosphor with long emission wavelength.…”

Blue-green tunable color of Ce3+/Tb3+ coactivated NaBa3La3Si6O20 phosphor via energy transfer

“…Then the average lifetime (τ*) can be calculated to be 24.5, 22.6, 21.7, 20.5, 20.0, 19.2 and 17.3 by the following formula4054:…”

Luminescence investigation and thermal stability study of Eu2+ and Eu2+–Mn2+ codoped (Ba,Sr)Mg2Al6Si9O30 phosphor

“…While, in order to obtain higher colorrendering index and tunable correlated color temperature, doubly doped luminescent material based energy transfer is considered to be an effective alternative for white LEDs. As we known, Mn 2+ doped luminescent materials have wide-range emissions from 500 to 700 nm depending on the crystal field of the host materials [7][8][9]. They could be good candidates for red phosphors, but the disadvantage of the Mn 2+ ions is that their d-d absorption transition is difficult to pump since it is strongly forbidden.…”