Multisite-Occupancy-Driven Efficient Multiple Energy Transfer: A Straightforward Strategy to Achieve Single-Composition White-Light Emission in Ce³⁺-, Tb³⁺-, and Mn²⁺-Doped Silicate Phosphors

Abstract

It is unquestionably true that site occupation and energy transfer play important roles in the luminescent properties of optical materials from both practical applications and theoretical research. In this paper, multisite-occupancy-driven multiple energy transfers were used as a straightforward strategy to achieve single-composition white-light emission in Ce3+-, Tb3+-, and Mn2+-doped Ba1.2Ca0.8SiO4 (BCS) phosphors. The Ce3+-, Tb3+-, and Mn2+-doped T-phase orthosilicate BCS samples were synthesized by traditional solid-state reactions. The phase composition was checked via X-ray diffraction (XRD), and the luminescent properties were systematically studied by photoluminescence spectroscopy and fluorescence decay curves. A detailed study on the efficient and multiple energy transfers of Ce I → Mn2+, Ce II → Tb3+, and Ce II → Tb3+ → Mn2+ was carried out. Satisfactorily, the selected phosphor exhibits a high internal quantum efficiency (QE) of 81% and good thermal stability. In addition, an evident negative thermal quenching phenomenon, i.e., the emission intensity increases with increasing temperature, is provided. Moreover, the mechanism of negative thermal quenching was proposed. On the basis of these excellent luminescence properties, a white LED with color-rendering index (R a = 89) was fabricated by integrating the phosphor on an n-UV 365 nm chip. These results show that the materials present potential application in the field of phosphor-converted white LEDs.

Experimental and Theoretical Studies of the Site Occupancy and Luminescence of Ce3+ in LiSr4(BO3)3 for Potential X-ray Detecting Applications

“…Because the crystal field strength has a strong influence on the outer 5d orbital of Ce 3+ , the 4f–5d transition energies of Ce 3+ may present remarkable variations in different coordination surroundings. Such a structural factor, which is controlled by site occupancy, directly governs the various aspects of the luminescence properties. − Apparently, a clear understanding of the site occupancy of Ce 3+ in the host compound is crucial for the development of novel lanthanide ion-doped luminescent materials with f–d transitions. To the best of our knowledge, a systematic analysis of the crystal field splitting (CFS) and centroid of Ce 3+ 5d energy levels is a good approach for gaining insight into the site occupancies of the doping Ce 3+ ions experimentally. , Furthermore, the first-principles calculations of the energies of f–d transitions corroborate the site occupancies, and those on the formation and transition energies of Ce 3+ ions in different sites give an explanation for the preferential occupancies theoretically. , …”

Luminescence and Energy Transfer of Color-Tunable Y2Mg2Al2Si2O12:Eu2+,Ce3+ Phosphors

“…13,14 Among them, utilizing the codoping strategy and energy transfer from sensitizers to activators is the most common and effective method. 15 According to previous reports, there are many common energy transfer systems, for example, Eu 2+ → Tb 3+ / Mn 2+ , 16,1716,17 Eu 2+ → Tb 3+ → Sm 3+ /Eu 3+ /Mn 2+ , 18,1918,19 Ce 3+ → Eu 2+ /Mn 2+ /Dy 3+ /Tb 3+ , 20,21 Ce 3+ → Tb 3+ → Sm 3+ /Eu 3+ / Mn 2+ , 9,229,22 Bi 3+ /Tb 3+ → Sm 3+ /Eu 3+ , 23,2423,24 and so on. Here, Ce 3+ and Eu 2+ are the most commonly used rare-earth ions in phosphor materials, and they exhibit broadband emission due to their 5d → 4f transition, which is very beneficial for applications in the lighting field.…”

“…For the color tuning of phosphors, there are many ways, such as controlling the doping levels, , adjusting the energy transfer process, , changing the structural construction, tuning the excitation wavelength, modifying the crystal field environment, and crystal-site engineering approach. , Among them, utilizing the codoping strategy and energy transfer from sensitizers to activators is the most common and effective method . According to previous reports, there are many common energy transfer systems, for example, Eu 2+ → Tb 3+ /Mn 2+ , , , Eu 2+ → Tb 3+ → Sm 3+ /Eu 3+ /Mn 2+ , , , Ce 3+ → Eu 2+ /Mn 2+ /Dy 3+ /Tb 3+ , , Ce 3+ → Tb 3+ → Sm 3+ /Eu 3+ /Mn 2+ , , , Bi 3+ /Tb 3+ → Sm 3+ /Eu 3+ , , , and so on. Here, Ce 3+ and Eu 2+ are the most commonly used rare-earth ions in phosphor materials, and they exhibit broadband emission due to their 5d → 4f transition, which is very beneficial for applications in the lighting field.…”

Energy transfer-triggered multicolor emissions in Tb3+/Eu3+-coactivated Y2Mo3O12 negative thermal expansion microparticles for dual-channel tunable luminescent thermometers

“…Obviously, the lifetime of Tb 3+ ions becomes shorter and shorter with raising the Eu 3+ ion content due to the ET from Tb 3+ to Eu 3+ ions. 32 Furthermore, it is widely accepted that the ET efficiency between sensitizer and activator can also be estimated from decay time by using the following expression: 33,34 (5)…”