Co-doped Phosphors Research Articles

Ce3+,Cr3+ co-doped garnet phosphors with yellow and near-infrared emission for white and near-IR dual-mode pc-LEDs

Ce3+,Cr3+ co-doped garnet phosphors with yellow and near-infrared emission for white and near-IR dual-mode pc-LEDs

Energy-Transfer-Enhanced Cr3+/Ni2+ Co-doped Broadband Near-Infrared Phosphor for Fluorescence Thermometers and Near-Infrared Window Imaging.

Here, near-infrared broad dual-band emission phosphors were achieved through energy transfer between Cr3+ and Ni2+ ions in the β-Ga2O3 host. All samples co-doped with Cr3+ and Ni2+ exhibit dual-band emission covering 600-1700 nm under 430 nm excitation. Thanks to the doping of Cr3+ ions, the emission intensity of Ga2O3:Cr3+, Ni2+ phosphors has increased by about 2.4 times and the internal quantum efficiency has increased by 83.2% compared to Ga2O3:Ni2+ phosphors. Meanwhile, when the fluorescence lifetime was monitored at 745 nm, an efficient energy transfer between Cr3+ and Ni2+ ions in the β-Ga2O3 host was verified. Due to the significant differences in the emission temperature-sensitive properties of Cr3+ and Ni2+ ions, a thermometer was designed utilizing fluorescence intensity ratio technology, achieving a maximum relative sensitivity of 5.26% K-1, which surpasses most optical temperature measurement phosphors. This suggests that Ga2O3:Cr3+, Ni2+ samples hold promise as potential candidates for optical thermometer materials. Additionally, the broadband near-infrared emission of the Ga2O3:Cr3+, Ni2+ sample has been investigated for potential applications in component analysis and night vision, demonstrating its versatility for multifunctional applications.

Upconversion enhancement and temperature sensing studies in Li+ ions incorporated GdPO4:Tm3+/Yb3+ phosphor

The GdPO4:Tm3+/Yb3+ phosphor codoped with various concentrations of Li + ions were synthesized for upconversion emission and optical thermometry studies. Excitation using 980 nm laser diode results in three upconversion (UC) emission bands with centre wavelengths of 478, 648 and 692 nm. These bands are originated from 1G4→3H6, 1G4→3F4, and 3F3→3H6 transitions of the Tm3+ ion, respectively. Li+ ions modified the local crystal symmetry around dopant ions, resulting enhanced UC emissions. The lifetime of the 1G4 level of Tm3+ ion was studied using a 980 nm laser excitation. The temperature sensing performances of GdPO4:Tm3+/Yb3+ and GdPO4:Tm3+/Yb3+/Li+ based on fluorescence intensity ratio (FIR) technique were evaluated in the temperature range 301–713 K under 980 nm excitation. Non-thermally coupled levels 3F3 (692 nm) and 1G4 (478, 648 nm) were utilized for FIR estimation. A maximum absolute sensitivity of 6.28 × 10−3 K−1 at 653 K and 18.71 × 10−3 K−1 at 713 K were observed for Li + undoped and codoped phosphors respectively. The result indicates that codoping of Li + ions improved the UC emission as well as optical thermometry. Moreover, CIE colour coordinates and anti-counterfeiting application were also exhibited.

Anti-thermal quenching and temperature sensing properties of Er3+/Yb3+ co-doped Sc2O3 phosphors

Up-conversion luminescence from rare earth doped phosphor is a potential candidate as non-contact temperature sensor. In this work, different Er3+ concentration doped Sc2O3: Er3+/Yb3+ phosphors were prepared through typical sol–gel method. The emission intensity reached the maximum as the doping concentration of Er3+ was 1.0 mol%. While, different from high concentration (0.5, 1.0 and 2.0) of Er3+ doped samples, an abnormal enhancement in the two green emissions and red emission in Sc2O3: 0.3 mol% Er3+/ 2 mol% Yb3+ phosphors was observed through elevate temperature and the enhancement factor reaches 1.3 as the temperature changed from 303 to 513 K. The reason for this concentration dependent thermal enhancement could be interpreted by the competition between increased energy transfer and non-radiative transition. The temperature sensing properties of samples, including relatively sensitivity, temperature resolution and repeatability were investigated and the maximum values reached 1.03 × 10−2 K−1 (303 K), 0.524 K (303 K) and 99.65 % (303––513 K), respectively, in Sc2O3: 1 mol% Er3+/2 mol% Yb3+ phosphors. The results imply that they have good temperature sensing ability and can be used as an optical temperature probe in research and production.

Up-conversion thermometry based on Tm3+/Yb3+ co-doped Ba5Gd8Zn4O21 phosphors

Optical thermometry based on fluorescence intensity ratio of rare earth ions has attracted widespread attention due to its non-contact, fast response time, immune to interference and high sensitivity. In this study, we developed Tm3+/Yb3+ doped Ba5Gd8Zn4O21 phosphors for temperature sensing purposes. The structure, morphology and luminescent performances of these phosphors were comprehensively explored using X-ray diffraction, scanning electron microscopy and photoluminescence techniques. Furthermore, we explored the temperature-dependent fluorescence intensity ratio of Tm3+ (1G4 → 3H6 and 3F2 → 3H6) with a temperature range of 303-573 K. Our results demonstrate excellent relative sensitivity and resolution for high-temperature sensing applications (SR = 1.94% K-1, ΔT = 0.61 K). Overall, our findings highlight the promising potential of BGZO:Tm3+/Yb3+ phosphors in optical thermometry sensing.

Photoluminescence investigations on Sm3+/Eu3+ co-doped Sr3NaSbO6 nanorod-shaped red phosphor for W-LEDs and indoor plant growth LEDs

Red phosphors have garnered an important role in white light-emitting diodes (W-LEDs). Herein we report the structural and luminescent properties of red-emitting Sr(3-x-y)NaSbO6: xSm3+/yEu3+ (SNSO: xSm; yEu) phosphors. Under 350 nm excitation, phosphors emit intense red emission peaking around 689 nm owing to the SNSO host emission. Optimized singly doped SNSO: 0.1Sm and SNSO: 0.2Eu phosphors have intense orange-red and red emissions under 405 and 305 nm excitations respectively. For the codoped SNSO: 0.1Sm; yEu phosphors (y = 0.1, 0.15, 0.2, 0.25, and 0.3 mol), the emission peaks of the host, Sm3+, and Eu3+ ions were present. The energy transfer from the host to Sm3+/ Eu3+ ions and from Sm3+ to Eu3+ ions was identified to be via dipole-quadrupole and quadrupole–quadrupole interactions respectively. Effective red tuning along with high color purity and warm CCT values suggest the suitability of prepared nanorod phosphors for W-LEDs and indoor plant growth LEDs.

Investigation of luminescence properties and energy transfer mechanism in Sm3+ and Eu3+ co-doped BaY2ZnO5 red phosphors

In this investigation, the photoluminescence properties, energy transfer phenomenon of BaY2ZnO5:Sm3+/Eu3+ doped/co-doped phosphor are reported and synthesized by high temperature solid state reaction method. The crystal structure, micromorphology, optical diffuse reflectance and photoluminescence properties of the samples were studied. The results show that concentration quenching phenomenon is found. With the increase of Eu3+ ion concentration, the emission peaks of Sm3+ gradually decrease, indicating that energy transfer between Sm3+ and Eu3+. The optimal concentrations are 0.05 mol and 0.2 mol for single doping Sm3+ and Eu3+, respectively. The energy transfer efficiency is calculated to be 78.47–95.19 %. The BaY2ZnO5 phosphors have potential application value in the fields of white light LEDs and anti-counterfeiting.

Enhanced temperature sensing in lead-free Cs3Bi2Cl9 perovskite co-doping Yb3+/Er3+ for optical thermometry application

A simple and rapid grinding method for preparing Er3+-doped and Er3+/Yb3+co-doped Cs3Bi2Cl9 upconversion phosphors was developed. We avoid to employ strong acids as reaction solvents, aligning with the principles of green chemistry. By controlling the thermal treatment temperature and adding BiCl3, a reversible phase transformation process between Cs3Bi2Cl9 and Cs3BiCl6 perovskite phosphors was achieved. The Er3+/Yb3+ co-doped Cs3Bi2Cl9 phosphors emit green light under 980 nm excitation, whereas Cs3BiCl6 phosphors emit red light. Their temperature sensing performance was tested through variable-temperature processes. Compared to Er3+-doped Cs3Bi2Cl9 phosphors, the co-doped Er3+/Yb3+ phosphors have a higher relative sensitivity of 1.60 % K−1. Compared to previously reported materials, Cs3Bi2Cl9 phosphors show enhanced sensitivity in temperature sensing. The study demonstrates that lead-free halide perovskites’ unique color-tunability not only underscores the innovativeness of this synthetic strategy but also provides a significant technological foundation for temperature sensing applications. Given their environmental friendliness and facile preparation process, these phosphors possess notable advantages for industrial production and hold promise as potential candidates for next-generation high-performance phosphor materials.

A Cr3+-Yb3+ co-doped high-efficiency near-infrared luminescent phosphor for NIR-II light source applications

Phosphor conversion light-emitting diode (PC-LED) technology has become a focal point of research for portable near-infrared light sources in recent years. One of the crucial aspects is to develop phosphor materials that can be effectively stimulated by commercial available blue light. Unfortunately, efficient phosphors in the NIR-II that can be excited by commercial blue light are particularly scarce. In this study, Mg4Ta2O9:0.04Cr3+,0.03Yb3+,0.07Li+ (MTO:0.04Cr3+,0.03Yb3+,0.07Li+) phosphor was synthesized using the high temperature solid phase method, and its emission spectrum covered the first and second near-infrared windows (700–1200 nm). The internal quantum efficiency (IQE) and external quantum efficiency (EQE) are 88.7 % and 45.6 %, respectively, due to the synergistic effect of energy transfer and Li-ion modification. Additionally, the doping of Yb3+ ions and Li+ ions enhances the thermal stability of luminescence. The thermal stability of MTO:0.04Cr3+,0.03Yb3+,0.07Li+ and MTO:0.04Cr3+,0.03Yb3+ is 9.81 % and 14.43 % higher, respectively, than that of MTO:0.04Cr3+,0.03Yb3+ and MTO:0.04Cr3+. To evaluate its potential applications, we developed a prototype PC-LED utilizing MTO:0.04Cr3+,0.03Yb3+,0.07Li+ phosphor as an emission emitter which demonstrated advantages in biomedical imaging, night vision, and non-destructive testing.

Novel Tm3+/Dy3+ co-doped CaMoO4 transparent glass-ceramic phosphor for white LED applications

To develop new inorganic luminescent materials, a set of Dy3+/Tm3+ co-doped molybdate precursor glasses (PGs) were manufactured using the conventional melting method, and a novel CaMoO4 transparent fluorescent glass-ceramic (GC700-2 h) was achieved via controlled crystallization of PG at 700 ℃ for 2 h. The luminescent color of the glass phosphor was facilely modulated by varying the doping levels of Dy3+ and Tm3+. The glass phosphor with optimal doping concentration of 0.6Dy3+ and 0.6Tm3+ exhibits a color coordinate of (0.3334, 0.3107). Compared with PG, the luminous intensity and quantum yield of GC700-2 h sample is obviously increased, and GC720-2 h sample displays the color coordinate (0.3292, 0.2852), belonging to the standard white light region. Moreover, GC720-2 h sample possesses good thermal stability in fluorescence property. The white LED lamp encapsulated with GC720-2 h exhibits color temperature of 7564 K and color rendering index of 75.3. These results clearly show that the 0.6Dy3+/0.6Tm3+ co-doped glass and CaMoO4 glass-ceramic could be used as potential candidate material in the field of white light-emitting diodes.

Up-Conversion Luminescence and Optical Temperature-Sensing Properties of Yb3+ and Er3+ Co-doped Yttrium Aluminum Garnet Phosphor

Up-Conversion Luminescence and Optical Temperature-Sensing Properties of Yb3+ and Er3+ Co-doped Yttrium Aluminum Garnet Phosphor

Cr3+ and Ni2+ Co-doped near-infrared dual-emission garnet phosphor for spectroscopic applications

Near infrared spectroscopy is a simple, fast, and non-invasive technique for detecting the composition of substances. However, most NIR phosphors cannot cover the near-infrared I and II regions, which limits the types of substances that can be detected. Herein, Cr3+, Ni2+ co-activated NIR Y3Al2Ga3O12(YAGG) garnet phosphors were synthesized via high-temperature solid-phase method. Due to the energy transfer from Cr3+ to Ni2+, the emission spectra of YAGG: Cr3+, Ni2+ are composed of NIR I emission of Cr3+ at 710 nm and NIR II emission of Ni2+ at 1420 nm. The measured internal and external quantum efficiencies of YAGG: 0.08Cr3+, 0.005Ni2+ under 450 nm excitation are 54.4 %, and 26.7 %, respectively. This sample was selected to fabricate pc-LEDs, and fill the emission spectrum gap with Mg2GeO4: 0.01Cr3+. The pc-LED fabricated with PiG film do not exhibit strong characteristic absorption in NIR II region, significantly reduce the re-absorption and thermal quenching of the phosphors. The electro-optical conversion efficiency of PiG pc-LED reaches 6.49 % at 10 mA; The results indicate that YAGG: Cr3+, Ni2+ and the fabricated NIR pc-LED are good near-infrared substance detection light source scheme.

RGB-tricolor multimodal luminescence of Ce3+ and Mn2+ in Mg2Al4Si5O18 via site occupancy engineering for anticounterfeiting applications

Multimodal luminescent materials have shown important applications in anti-counterfeiting and information encryption, however, mostly difficult to adjust optical properties with the structure, which leads to relatively constant emission position and less selectable excitation wavelength. Herein, Ce3+ and Mn2+ co-doped Mg2Al4Si5O18 phosphors are designed for the applications in RGB-tricolor multimodal anti-counterfeiting. Due to site occupancies, energy transfer and different thermal behaviors of Ce3+ and Mn2+ emissions, the emitting color of Mg2Al4Si5O18: Ce3+, Mn2+ is rich and tunable with different excitation wavelengths, doping concentrations and temperatures. The site occupancies of Ce3+ and Mn2+ are clarified with crystal field analysis and in-depth into transitions energies of Ce3+ and Mn2+. The energy transfer mechanism between Ce3+ and Mn2+ is analyzed via Inokuti-Hirayama model. The difference of thermal stabilities of Ce3+ and Mn2+ emissions is interpreted with construction of vacuum referred binding energy scheme. The as-designed molds of information encryption and decryption with Mg2Al4Si5O18: Ce3+, Mn2+ phosphors demonstrate the potential applications in anti-counterfeiting. The work provides an effective way for exploring Ce3+ and Mn2+ doped phosphors with RBG-tricolor multimodal luminescence.

La3Sc2Ga3O12:Cr3+, Nd3+ near-infrared phosphor for nondestructive detection and luminescence thermometry

To develop continuous broadband emission near-infrared (NIR) phosphors compatible with blue LED chips, numerous Cr3+-Yb3+ co-doped phosphors have been synthesized. However, the emission spectra of Cr3+ vary significantly across different matrix materials, while Yb3+ maintains a relatively stable emission spectrum. This variation leads to notable luminescence depressions between 850 and 900 nm in many Cr3+-Yb3+ co-doped phosphors. To address this emission spectrum gap, we utilized Cr3+ as a sensitizer and introduced Nd3+ as the luminescence center within the La3Sc2Ga3O12 matrix material, establishing a Cr3+-Nd3+ energy transfer channel. Under 480 nm excitation, we tuned emission peaks at 800 nm (Cr3+) and 881 nm (Nd3+). The stable NIR emission of Nd3+ effectively compensates for the missing spectrum in Cr3+-Yb3+ co-doping. The Cr3+-Nd3+ energy transfer process was thoroughly analyzed using diffuse reflection spectrum, excitation spectrum, and fluorescence decay curves. The LSGO:0.125Cr3+, 0.03Nd3+ compound with the best optical performance was packaged with a 480 nm LED chip to create a NIR light source. At a working current of 10 mA, it achieved a photoelectric conversion efficiency of 9.45 %, demonstrating its potential for applications in non-destructive detection and luminescence thermometry. This work presents a novel strategy for tuning NIR spectral distribution and developing continuous broadband NIR phosphors.

Highly thermostable and color tunable Dy3+/Sm3+ co-doped germanate phosphors for solid-state lighting

Currently, developing thermostable and color tunable phosphor via energy transfer strategy is a significant research topic in solid-state lighting field. Herein, the sensitizer Dy3+ and activator Sm3+ are solidly dissolved into the Ba2Y2Ge4O13 (BYGO) matrix to prepare color-tunable germanate phosphors BYGO:Dy3+,Sm3+. Under 365 nm excitation, the energy transfer-induced tunable emission of Dy3+/Sm3+ co-doped phosphors are investigated. The energy transfer mechanism is ascribed to the quadrupole-quadrupole interaction. The thermal quenching investigation manifests that the BYGO:Dy3+,Sm3+ phosphor has excellent thermostability (the emission intensity at 423 K reduces only 6.9 %) and resistance to chromaticity shifting (the chromaticity shifting parameter at 473 K is as low as 3.94 × 10−3). Meanwhile, the ∼365 nm InGaN chip-excited w-LED device is fabricated with commercial phosphor BaSi2O2N2:Eu2+ and the title material, showing satisfactory electroluminescence performance. This work reveals that the title phosphor is a suitable candidate for solid-state lighting.

Solid-state reaction synthesis of LuPO4:Yb3+, Tb3+ phosphors and the ultraviolet/near-infrared responsive spectra performances

Yb3+/Tb3+ co-doped LuPO4 phosphors were prepared by solid-state reaction method. The effects of Yb3+/Tb3+ doping concentrations on the downshifting and upconversion spectral performances of the synthesized phosphors were investigated. Upon the ultraviolet light excitation, the phosphors show obvious visible light emission, which can be assigned to the 5D4→7FJ (J=6, 5, 4, and 3) transitions of Tb3+ ions respectively, the green light emission at 543 nm is dominant. Upon 980 nm excitation, the phosphors display intense green and blue light emission, and weak yellow and red light emission, which originates from the cooperative energy transfer process between Yb3+ and Tb3+ ions. The synthesized LuPO4:Yb3+, Tb3+ phosphors show good ultraviolet/near-infrared responsive spectra, color-tunable and thermal-stability performances and may have potential applications in the related fields.

Highly sensitive dual-mode temperature measurement utilizing completely opposite thermal quenching luminescence

In recent years, phosphors have been used in the field of temperature sensing, which has aroused great interest because of its advantages of quick response, high sensitivity and high accuracy. However, exploring optical thermometers with ultra-high sensitivity remains a challenge. In this work, we have designed and synthesized Sm3+ and Mn4+ co-doped La3Mg2NbO9 phosphor for temperature sensing for the first time by utilizing the anomalous thermal quenching property of Sm3+ ions and the sensitive thermal quenching property of Mn4+ ions. Furthermore, the structure, elemental distribution, morphology and optical characteristics of La3Mg2NbO9:Sm3+,Mn4+ were studied in detail. Benefiting from the different responses of the Sm3+ and Mn4+ ions to temperature, the fluorescence intensity ratios of Sm3+ to Mn4+ in La3Mg2NbO9 samples show excellent optical thermometry performance in the range of 303–463 K. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) values of La3Mg2NbO9:Sm3+,Mn4+ sample reach as high as 0.117 K-1 (@463 K) and 4.48 % K−1 (@303 K), respectively. Furthermore, the maximum of Sa is 0.385 K−1 (@463 K) and the maximum of Sr is 4.54 % K−1 (@303 K) based on the fluorescence lifetime temperature measurement method. The temperature cyclotron curve of the sample proves that the sample has excellent stability and repeatability in temperature measurement. These results demonstrate that the designed La3Mg2NbO9:Sm3+,Mn4+ phosphor is promising for the field of non-contact optical temperature thermometry.

Strong red upconversion luminescence of Yb3+/Er3+ co-doped Sc6WO12 phosphor for optical thermometry

Herein, a strong red upconversion phosphor of Yb3+/Er3+ co-doped Sc6WO12 was prepared by employing an equivalent substitution approach. When irradiated by 980 nm near-infrared laser, the phosphor emits strong 660 nm red light. The main excitation mechanism for its red upconversion luminescence emission is the energy transfer process, through which the Er3+ ions is promoted from the 4I13/2 energy level to the 4F9/2 energy level. In addition, it is noteworthy that the multimode upconversion luminescence phosphor exhibits three different trends upon temperature change, and its upconversion emission integral intensity ratio exhibits a linear relationship with temperature in the range of 298 K–623 K. This special property makes the phosphor promising for applications in optical temperature measurement.

Study on the Luminescence Performance and Anti-Counterfeiting Application of Eu2+, Nd3+ Co-Doped SrAl2O4 Phosphor.

This manuscript describes the synthesis of green long afterglow nanophosphors SrAl2O4:Eu2+, Nd3+ using the combustion process. The study encompassed the photoluminescence behavior, elemental composition, chemical valence, morphology, and phase purity of SrAl2O4:Eu2+, Nd3+ nanoparticles. The results demonstrate that after introducing Eu2+ into the matrix lattice, it exhibits an emission band centered at 508 nm when excited by 365 nm ultraviolet light, which is induced by the 4f65d1→4f7 transition of Eu2+ ions. The optimal doping concentrations of Eu2+ and Nd3+ were determined to be 2% and 1%, respectively. Based on X-ray diffraction (XRD) analysis, we have found that the physical phase was not altered by the doping of Eu2+ and Nd3+. Then, we analyzed and compared the quantum yield, fluorescence lifetime, and afterglow decay time of the samples; the co-doped ion Nd3+ itself does not emit light, but it can serve as an electron trap center to collect a portion of the electrons produced by the excitation of Eu2+, which gradually returns to the ground state after the excitation stops, generating an afterglow luminescence of about 15 s. The quantum yields of SrAl2O4:Eu2+ and SrAl2O4:Eu2+, Nd3+ phosphors were 41.59% and 10.10% and the fluorescence lifetimes were 404 ns and 76 ns, respectively. In addition, the Eg value of 4.98 eV was determined based on the diffuse reflectance spectra of the material, which closely matches the calculated bandgap value of SrAl2O4. The material can be combined with polyacrylic acid to create optical anti-counterfeiting ink, and the butterfly and ladybug patterns were effectively printed through screen printing; this demonstrates the potential use of phosphor in the realm of anti-counterfeiting printing.

Synthesis and Characterization of Color Tunable Europium(III) and Terbium(III) Co-Doped LaSrAl3O7 Nanocrystalline Phosphors: A Photoluminescent Synergy

Synthesis and Characterization of Color Tunable Europium(III) and Terbium(III) Co-Doped LaSrAl3O7 Nanocrystalline Phosphors: A Photoluminescent Synergy