Strategic Tuning of Photophysical Response in the Polyhedral Framework of the Garnet Structure toward White Light-Emitting Devices with Enhanced Color Rendering

Abstract

Designing a single-phase phosphor with high quantum efficiency and full spectrum emission is inevitable for today’s scientific world. Herein, an optimal strategy for realizing white emission in a single component matrix is envisaged based on the structure–property-design-device policy. Cationic substitution corresponding to polyhedral expansion and contraction in A2A′B2V3O12 confirms the existence of strong and intricate linkage in the garnet structure. The dodecahedral expansion causes compression of VO4 tetrahedra and a blue shift. The direct correlation of V–O bond distance with red shift validates the distortion of the VO4 tetrahedra. The interdependence of photophysical properties via cationic substitution and subsequent correlation of the V–O bond distance with emission bands enabled the tailoring of phosphor-CaSrNaMg2V3O12 with a high quantum efficiency of 52% and excellent thermal stability of 0.39 eV. Bright warm white light-emitting diode (WLED) devices are fabricated based on Eu3+ and Sm3+-activators. A high quantum efficiency-74% is obtained for the designed Eu3+ phosphor. CIE coordinates near the achromatic point (0.329, 0.366), low CCT-5623 K, and high color rendering index (CRI)-87 are obtained for the single-phase WLED device. This work puts forth a new direction for designing and engineering promising WLEDs with enhanced color rendering based on single-phase phosphors with full spectrum emission.

Augmenting cyan emission in vanadate garnets via Dy3+activation for light emitting devices and multi-mode optical thermometry

“…3(b), indicating that the phosphor can be suitably excited by NUV radiation. Compared with the SNMV host (3.2 eV), 4 the slight decrease in the bandgap is due to the occupation of smaller Dy 3+ ions in the dodecahedral site occupied by larger Sr 2+ ions. The presence of wide and direct bandgap indicates the potentiality of the material for lighting applications.…”

“…Over the years, light-emitting devices based on solid-state technology have made profound advancements in lighting due to their benefits, such as energy efficiency, an extended lifetime, low energy consumption, environmental friendliness, and so on. 1–4 Nevertheless, the commercially available devices based on a blue LED and yellow phosphor, YAG:Ce 3+ , are limited by their low color rendering index due to the lack of the red emission component. As a solution to this problem, the combination of red-green-blue phosphors with the NUV chip is introduced.…”

“…12,13 In various vanadate-based phosphor systems, the garnet structure offers more freedom to tune the emission owing to the unique structural framework, flexibility in cation substitution, and compositional diversity. 1,4,14 The general stoichiometry of the garnet structure is A 3 B 2 C 3 O 12 where A, B, and C correspond to dodecahedral, octahedral, and tetrahedral sites. In particular, for vanadate garnets, the tetrahedral complex VO 4 3− is interlinked with the structural changes in the neighborhood.…”

Delving into the multifunctionality of Sr2NaMg2V3O12via RE3+ substitution for dual-mode temperature sensing, latent fingerprint detection and security inks

“…Consequently, the lattice parameter decreases from 12.654(1) Å (SNMV) to 12.652(1) Å (SNMV:0.05Sm) and 12.644(8) Å (SNMV:0.12Sm) respectively. 22 The Rietveld refinement and crystallographic parameters of SNMV:0.12Sm 3+ are tabulated in Table S2 (ESI†).…”

“…Vanadate-based hosts are known for their strong absorption and self-activated luminescence due to the 3 T 1,2 → 1 A 1 transitions. 17,19–24 RE ions possess a low absorbance in the UV region due to narrow excitation of forbidden 4f–4f transition. Hence, the RE-activated vanadate host structure helps in phonon-assisted energy transfer from VO 4 3− to RE 3+ .…”