Luminescence and Energy-Transfer Properties in Bi³⁺/Mn⁴⁺-Codoped Ba₂GdNbO₆ Double-Perovskite Phosphors for White-Light-Emitting Diodes

Abstract

Currently, the study of Mn 4+ -doped oxide red phosphor is a hot research topic to solve the lack of red component in phosphor-converted whitelight-emitting diodes (pc-WLEDs). In this Article, we designed Gd 3+ /Nb 5+ cation substitution by Bi 3+ /Mn 4+ in Ba 2 GdNbO 6 with double-perovskite structure based on the radius and coordination of the cations through hightemperature solid-state reaction. The phase purity and microstructure of double-perovskite Ba 2 GdNbO 6 :Bi 3+ ,Mn 4+ phosphors were characterized by Xray diffraction and scanning electron microscopy examination. The crystal structures were also determined by the Rietveld refinement, and the photoluminescence (PL) properties were systematically studied. Bi 3+ and Mn 4+ ions can be effectively doped in the Ba 2 GdNbO 6 matrix with an optical band gap of 3.94 eV. Upon 315 nm UV excitation, the Ba 2 GdNbO 6 :Bi 3+ ,Mn 4+ phosphor shows two emission bands at 464 nm from Bi 3+ and 689 nm from Mn 4+ , respectively. By the design of Bi 3+ → Mn 4+ energy transfer, systematic luminescence tuning from blue to red could be achieved because of spectral overlap between the emission spectrum of Bi 3+ and the excitation spectrum of Mn 4+ . The corresponding mechanism of the Bi 3+ → Mn 4+ energy-transfer process was investigated in detail by the fluorescence decays and PL spectra. The red emission intensity of Mn 4+ has been greatly improved by Bi 3+ → Mn 4+ energy transfer. Moreover, the phonon vibration and zero phonon line of Mn 4+ were studied through temperature-dependent PL. Finally, a WLED was fabricated using a 460 nm blue chip with a yellow YAG:Ce 3+ phosphor and a red Ba 2 GdNbO 6 :0.01Bi 3+ ,0.01Mn 4+ phosphor, which has a low correlated color temperature (3550 K) and a high color rendering index (89.6). The above results imply that the improved red emission phosphors have a potential application in warm pc-WLED lighting.

Charge transfer band excitation of La3NbO7:Sm3+ phosphors induced abnormal thermal quenching toward high‐sensitivity thermometers

“…[15][16][17] Several niobates acting as host materials for doping RE ions have drawn wide interest due to the good thermal stability, remarkable chemical stability, and strong emission intensity. [18][19][20][21] It should be noted that the La 3 NbO 7 host has an orthorhombic space group of Cmcm. There are two kinds of La sites.…”

Obtaining Efficiently Tunable Red Emission in Ca3-δLnδWO6:Mn4+ (Ln = La, Gd, Y, Lu, δ = 0.1) Phosphors Derived from Nearly Nonluminescent Ca3WO6:Mn4+ via Ionic Substitution Engineering for Solid-State Lighting

“…Therefore, as an alternative, the nonrare earth ion Mn 4+ (3d 3 electronic configuration)-activated phosphors was noticed by scientists and rapidly received considerable attention due to its good chemical stability, desirable spectral features, and low cost. It can exhibit broad and strong absorption in the range of 200–600 nm attributed to Mn 4+ 4 A 2g → ( 4 T 1g , 2 T 2g , and 4 T 2g ) transitions and simultaneously gives rise to stable red to far red light ranging from 600 to 780 nm owing to Mn 4+ 2 E g → 4 A 2g spin-forbidden transition. , In addition, Mn 4+ prefers to accommodate into octahedral sites with center ions such as Al 3+ , Sc 3+ , Si 4+ , Ge 4+ , Zr 4+ , Nb 5+ , Ta 5+ , W 6+ , and Te 6+ − to generate the luminescence which depends on the covalence and coordination symmetry around the Mn 4+ in the host. To date, two primary groups of fluorides and oxides have been adopted as the hosts for Mn 4+ doping.…”

Achieving Efficient Red-Emitting Sr2Ca1−δLnδWO6:Mn4+ (Ln = La, Gd, Y, Lu, δ = 0.10) Phosphors with Extraordinary Luminescence Thermal Stability for Potential UV-LEDs Application via Facile Ion Substitution in Luminescence-Ignorable Sr2CaWO6:Mn4+

“…It is well known that phosphor-converted light-emitting diodes (pc-LEDs) have been considered as the next-generation light source system on account of their attractive merits comprising low energy consumption, compactness, high luminescence efficiency, non-environmental contamination, long working lifetime, which thus will be practically used in lighting and display devices. − In addition, with the employment of various LED chips with spectral conversion materials, the huge spectral tuning within visible-near infrared region in pc-LEDs can be realized according to the requirement . Recently, an alternative way to get higher quality white light by combining ultraviolet (UV)/near-UV LEDs chips with blue, green, and red phosphors is proposed since current blue LED chips + Y 3 Al 5 O 12 :Ce (YAG:Ce) mode lacks red component leading to a low color rendering index (CRI) and high related color temperature (CCT). , On the other hand, the grown LEDs application as artificial lighting source for indoor plant cultivation requires the blue (400–500 nm) and red-far-red (600–780 nm) light to prompt the reactions of photosynthesis, phototropism, and photomorphogenesis in plants .…”