Color Tuning Of Upconversion Emission Research Articles

Instantaneous Color Tuning of Upconversion Emission in a Novel Lanthanide-Doped Monolithic Glass via Excitation Modulation

In this work, instantaneous tuning of emission color in a monolithic tellurite glass doped with Ho3+/Tm3+/Yb3+ ions by modulating excitation frequency is experimentally demonstrated for the first t...

The synergistic effect of Er3+ and Ho3+ on temporal color tuning of upconversion emission in a glass host via a facile excitation modulation technique for anti-counterfeiting applications.

Lanthanide-doped upconversion luminescent materials are highly promising for diverse applications, e.g., solid-state lighting, volumetric displays, and anti-counterfeiting, owing to their unique optical feature of color-tunable emission under near-infrared excitation. Hence, in this study, emission color tuning of Er3+/Ho3+ ions in a fixed glass host is investigated via a facile excitation modulation technique. The upconversion emission color from green to yellowish is tuned successfully by regulating the frequency of the irradiation source. The population and depopulation rates of related transitions are investigated through time-resolved photoluminescence and Judd-Ofelt analysis in order to elucidate the proposed mechanism of color tuning. Upconversion quantum yield values are measured in the range of 0.12 to 0.17% for a better comparison of the emission properties. Additionally, thermal, and structural properties are investigated to reveal the favorable properties of the selected tellurite glass host. Ultimately, several patterns are designed and constructed by a screen-printing technique using powdered glass to demonstrate its suitability as a multicolor imaging method for anti-counterfeiting applications. The temporal color tuning of upconversion emission via a facile excitation modulation technique in a glass host clearly indicates that the proposed Er3+/Ho3+ co-doped glasses can be potentially applied in the state-of-the-art technologies, especially for anticounterfeiting purposes.

Color tuning of up-conversion emission in ytterbium, erbium, aluminum tri-doped zinc oxide crystal by adjusting aluminum concentration

ABSTRACTYtterbium, erbium, aluminum tri-doped zinc oxide crystal was synthesized, which can turn color from red to green up-conversion luminescence through adjusting aluminum content. When the aluminum concentration reached 4 mol%, the color of up-conversion emission first turn from red to green. Meanwhile, the ratio of red to green emission reduced from 25.32 to 0.26, and the coordinates of chromaticity coordinate calculation changes from (0.5749, 0.3378) to (0.2190, 0.7169) with aluminum concentration range from 0 to 4 mol%. The up-conversion emission peaks at 521, 542, and 660 nm of sample originate from the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of erbium ions, respectively. X-ray diffraction patterns perform the better crystallization degree with increasing aluminum concentration. The scanning electron microscopy images show the porous and lamellar structures with different aluminum concentrations. A convenient but effective design to obtain ytterbium, erbium, aluminum tri-doped zinc oxide up-conversion luminescence is reported, which can turn color from red to green.

Color-tunable emission by adjusting sensitizer (Yb3+) and excitation power of 980 nm in NaGdTiO4:Yb3+/Tm3+/Er3+ phosphors for light emitting diodes

Color-tunable upconversion emission was explored in the NaGdTiO4 synthesized by a high temperature solid-state reaction process. NaGdTiO4:Er3+, NaGdTiO4:Yb3+/Tm3+ and NaGdTiO4:Yb3+/Er3+ are mainly dominated by green, blue and yellow light emissions under 980nm diode laser, respectively. The intensity ratios of red to green luminescence and blue to green luminescence increase with increasing the concentration of Yb3+ in NaGdTiO4:Yb3+/Tm3+/Er3+ phosphors. Changing the power of laser can influence the photon transfer pathways and eventually tune the emission colors. Additionally, the laser excitation heating effect and the temperature dependent spectra were also investigated, which indicated that the laser-induced heating effect was not the main reason for the laser power to change the emission. The CIE chromaticity coordinates of NaGdTiO4:60%Yb3+/1%Tm3+/5%Er3+ are close to the standard white light (x = 0.33, y = 0.33) and the sample has a good thermal stability. The strategies for color tuning of upconversion emission proposed in the NaGdTiO4 would be beneficial to achieve efficient multicolor (including white light) luminescence.

Synthesis of hollow La2O3:Yb3+/Er3+/Tm3+ microspheres with tunable up-conversion luminescence properties

Hollow La2O3:Ln3+ (Ln3+ = Yb3+, Er3+, Tm3+) microspheres were successfully synthesized via a facile sacrificial template method by employing PS spheres as hard template followed by a subsequent heating process. The structure, morphology, and formation process are well investigated by various techniques. A systematic study on the up-conversion (UC) PL properties of La2O3:Yb3+/Er3+/Tm3+ products have been performed in detail. Under 980 nm laser diode excitation, La2O3:Yb3+/Tm3+, La2O3:Er3+ and La2O3:Yb3+/Er3+ products are mainly dominated by blue, green, and red light emissions, respectively. By increasing Er3+ concentration, the La2O3:Er3+ gives yellow emission. Furthermore, the UC white light was successfully obtained in the La2O3:Yb3+/Er3+/Tm3+ system by adjusting the relative doping concentration of Yb3+, Er3+ and Tm3+. The obtained UC white light can be tuned at a wide range, and the optimal white-emitting CIE (Commission internationale de l'eclairage [International Commission on Illumination]) chromaticity coordinate is (x = 0.3250, y = 0.3180), which is very close to the standard equal energy white light (x = 0.33, y = 0.33). The strategies for color tuning of up-conversion emission proposed in the current system may be helpful for other ones to achieve efficient multicolor (including white light) luminescence under 980 nm laser excitation. Because of abundant luminescent colors from RGB to white in La2O3:Yb3+/Er3+/Tm3+ samples under 980 nm laser diode (LD) excitation, they can potentially be used as fluorophores in the field of color displays, back light, UC lasers, and photonics.

Multiform La2O3: Yb3+/Er3+/Tm3+ submicro-/microcrystals derived by hydrothermal process: Morphology control and tunable upconversion luminescence properties

LaCO3OH:Ln3+ (Ln = Yb, Er, Tm) submicro/microcrystals with a variety of novel and well-defined morphologies including triagonal or truncated triagonal-prism/plate, hexagonal prism, pine nut and sphere have been synthesized via a facile hydrothermal route. A series of controlled experiments indicate that the inherent crystal structure and the external experimental conditions such as the pH values in the initial reaction systems, the volume ratio of EG to H2O, and the dosage of CO(NH2)2 were responsible for shape determination of the LaCO3OH products. The possible formation mechanism for these diverse architectures has been presented. After annealing at a suitable temperature, the as-prepared LaCO3OH:Ln3+ crystals were easily converted to La2O3:Ln3+ without changing their original morphologies. A systematic study on the upconversion (UC) PL properties of La2O3:Yb3+/Er3+/Tm3+ products have been performed in detail. Under 980 nm laser diode excitation, La2O3:Yb3+, Tm3+, La2O3:Er3+ and La2O3:Yb3+, Er3+ products are mainly dominated by blue, green and red light emissions, respectively. By increasing Er3+ concentration, the La2O3:Er3+ gives yellow emission. Furthermore, the UC white light was successfully obtained in the La2O3:Yb3+/Er3+/Tm3+ system by adjusting the relative doping concentration of Yb3+, Er3+ and Tm3+. The obtained UC white light can be tuned at a wide range, and the optimal white-emitting CIE (Commission internationale de l'eclairage [International Commission on Illumination]) chromaticity coordinate is (x = 0.3259, y = 0.3187), which is very close to the standard equal energy white light (x = 0.33, y = 0.33). The strategies for color tuning of upconversion emission proposed in the current system may be helpful for other ones to achieve efficient multicolor (including white light) luminescence under 980 nm laser excitation.