Red Upconversion Research Articles

Concentration dependence of upconversion luminescence of Er3+/Yb3+ in the fluorophosphate glasses with small phosphates content

Abstract Frequency upconversion into green and red luminescence in fluorophosphate glasses doped with Er3+ ions (1021 to 1016 ion/cm3) and Yb3+ ions (1021 ion/cm3) while pumped with a 970 nm diode laser is presented. The red upconversion emission results from a two-photon excitation process. The upconversion emission intensity dependence on the incident pump power shows that the green upconversion luminescence arising from 2H11/2 level is also contributed by the two-photon processes. The values of n-parameter for the 4S3/2 level change from 2.7 to 2.0 during low power excitation and continue decreasing at higher pumping energy. It has been shown that the green upconversion luminescence intensity dependence on the erbium ions content has a sharp maximum at the concentration of 2* 1019 ion/cm3. We attribute the high upconversion luminescence in case of low Er3+ and Tm3+ ions concentrations (about 1018–1016 ion/cm3) to the cooperative energy transfer from Yb–Yb* dimers. The formation of excited dimers is confirmed experimentally by cooperative luminescence band at 495 nm.

Simultaneous improvement in emission intensity and spectral purity of red photon upconversion in Gd2O3:Yb3+/Er3+ phosphors under 1550 nm excitation

Upconversion luminescent nano-materials with both excitation and emission peaks in the “optical window” is of significant importance for application in deeper bio-imaging, due to the weak effects of light absorption, light scattering, and auto-fluorescence. This paper reports an Er3+ self-sensitized red up-converting nanophosphors with improved emission intensity and spectral purity. The influence of Yb3+ concentration on upconversion luminescence properties is investigated comprehensively. Compared with the sample without Yb3+ doping, the luminescence intensity in the sample with 10% Yb3+ is increased by 12.9 times. Moreover, the dominant wavelength at 1550 nm excitation is about 60 nm larger than that excited at 980 nm. It has been demonstrated that Yb3+ co-doping can not only improve the photon absorption at 1550 nm and the probability of red emission, but also suppress other light emissions and phonon emission through the selective population of red-emitting level.

Efficient NIR to NIR up-conversion in LiYF4:Yb3+,Tm3+ micro-octahedrons by modified hydrothermal method

The efficient NIR-to-NIR upconverter of LiYF4:Yb3+,Tm3+ (simplified as LYF:Yb,Tm) was synthesized by a modified hydrothermal method in this work. The synthesized LYF:Yb,Tm has well controlled morphology of monodisperse micrometer sized octahedrons. XRD pattern confirms its pure tetragonal LiYF4 structure. The LYF:Yb,Tm exhibits a dominating NIR UC emission at ~793 nm along with relative weak blue and red UC emissions under 976 nm LD excitation. The optimal concentrations of Yb3+ and Tm3+ ions for NIR up-conversion (UC) emission are 20 mol% and 0.6 mol%, respectively. The internal UC quantum yield (IUCQY) of this LYF:Yb,Tm in NIR band is tested to be 5.1% at 959 nm LD excitation power density (PD) of 120 W/cm2. The UC emission mechanism is discussed based on UC fluorescent behaviors of Yb3+ and Tm3+. The results of fluorescent labeling indicate its potential applications in fluorescent markers, solar cells and 3D flat panel displays.

Dual-Wavelength Excited Intense Red Upconversion Luminescence from Er3+-Sensitized Y2O3 Nanocrystals Fabricated by Spray Flame Synthesis.

Er3+-sensitized upconversion nanoparticles (UCNPs) have attracted great attention due to their tunable upconversion (UC) emissions, low cytotoxicity, high resistance to photobleaching and especially multiple effective excitation wavelengths. However, detailed energy conversion between Er3+ and Tm3+ ions in Y2O3 UCNPs is still a problem, especially under multi-wavelength and variable pulse width excitation. In this work, we successfully fabricated a series of Er3+-sensitized Y2O3 nanocrystals by a spray flame synthesis method with a production rate of 40.5 g h−1. The as-prepared UCNPs are a pure cubic phase with a mean size of 14 nm. Excited by both 980 and 808 nm lasers, the tunable upconversion luminescence (UCL) from Er3+ ions was achieved by increasing the Er3+ doping concentration, co-doping Tm3+ ions and extending excitation pulse-width. The investigations of the lifetimes and the laser power dependence of UC emissions further support the proposed mechanism, which provides guidance for achieving effective color control in anticounterfeiting and multiplexed labeling applications. In addition, the red UC emission at about 5 mm beneath the tissue surface was observed in an ex vivo imaging experiment under the excitation of 808 nm laser, indicating that the Y2O3:Er3+/Tm3+ UCNPs have great prospects in further biological applications.

Influence of Cr3+ on yellowish‐green UC emission and energy transfer of Er3+/Cr3+/Yb3+ tri‐doped zinc silicate glasses

AbstractIn this paper, we study the influence of Cr3+ on yellowish‐green upconversion (UC) emission and the energy transfer (ET) of Er3+/Cr3+/Yb3+ tri‐doped in SiO2–ZnO–Na2O–La2O3 (SZNL) zinc silicate glasses under excitation of the 980 nm laser diode (LD). The influence of Cr3+ on enhancing the red UC emission of Er3+/Cr3+/Yb3+ tri‐doped in SiO2–ZnO–Na2O–La2O3 zinc silicate glasses under the excitation of 980nm LD was also investigated. The ET processes between Yb3+, Cr3+, and Er3+, together with the combination of Yb3+‐Cr3+‐Er3+, which led to the green UC emission intensity of Er3+/Cr3+/Yb3+ tri‐doped in SiO2–ZnO–Na2O–La2O3 zinc silicate glasses bands centered at ~546 nm have been significantly enhanced. By increasing the concentration of Cr3+ from 0 up to 5 mol.%, we can locate the Commission Internationale de l'éclairage (CIE) 1931 (x; y) chromaticity coordinates for UC emissions of Er3+/Cr3+/Yb3+ tri‐doped in the central position of the yellowish‐green color region of CIE 1931 chromaticity diagram. Besides, the ET processes between the Yb3+, Cr3+, and Er3+ are also proposed and discussed.

Spectral characteristics and optical temperature sensing properties of Er3+/Yb3+-co-doped phosphate glasses with GeO2 modification.

Er3+/Yb3+-co-doped phosphate glasses with GeO2 modification (PLAZGs) were successfully prepared by the melt-quenching method. The phenomenological intensity parameters Ωt (t=2, 4, 6) of the PLAZGs have been calculated by the Judd-Ofelt theory. Based on the phenomenological intensity parameters, the spectroscopic parameters of Er3+ and fluorescence intensity ratio (FIR) of green upconversion emissions were estimated. It was observed that, under 980 nm excitation, all samples exhibit green and red upconversion emissions of Er3+. The 10 mol% GeO2 modified phosphate glass has the strongest upconversion emission. Additionally, the fluorescence decays of the 2F5/2→2F7/2 transition of Yb3+ ions were measured to evaluate the energy transfer efficiency from Yb3+ to Er3+ ions. Finally, the optical temperature sensing properties based on upconversion emissions were investigated at temperatures from 150 K to 600 K. The maximum absolute temperature sensitivity S value of 6.0×10-3K-1 at 400 K is obtained, which indicates that the glass is promising for temperature sensing application based on the FIR technology.

Crystal structure and up-conversion luminescence properties of K3ScF6:Er3+,Yb3+ cryolite

In this paper, K3ScF6:Er3+,Yb3+ up-conversion luminescent materials with cryolite structure were synthesized via solid-state method. The X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL) under the excitation of a 980 nm laser with different power density were used to investigate the phase structure, elemental composition, and up-conversion luminescence properties of K3ScF6:Er3+,Yb3+. The quenching concentrations of Yb3+ and Er3+ were confirmed to 0.15 and 0.05 (mol concentration) in this system, respectively. Upon 980 nm excitation, the K3ScF6:Er3+,Yb3+ showed a typical transition of Er3+ which contains two main bands in the visible region that green and red. According to the fitting result of the pump power dependence of up-conversion intensity, all the green and red up-conversion emission of K3ScF6:0.05Er3+,0.15 Yb3+ belong to the two-photon process. To better understand the origin of radiation and energy transfer mechanism of the red and green up-conversion, the possible mechanism and electron transition process were also discussed.

Deep-Tissue Temperature Sensing Realized in BaY2O4:Yb3+/Er3+ with Ultrahigh Sensitivity and Extremely Intense Red Upconversion Luminescence.

In this paper, BaY2O4:Yb3+/Er3+, a high efficient red upconversion (UC) material, is first utilized as an optical thermometer in the biological window, accomplished through the fluorescence intensity ratio (FIR) of thermally coupled Stark sublevels of 4F9/2 (FIR(654/663)). The maximum absolute sensitivity of FIR(654/663)) is 0.19% K-1 at 298 K, which is much higher than most previous reports about FIR-based temperature sensors located in the biological windows. More importantly, the groove of FIR(654/663) for thermometry is nicely located in the physiological temperature range, indicating its potential thermometry application value in biomedicine. Furthermore, a simply ex vivo experiment is implemented to evaluate the penetration depth of the red emission in biological tissues, revealing that a detection depth of 6 mm can be achieved without any effect on the FIR values of I654 to I663. Beyond that, the temperature sensing behaviors of the thermally coupled levels 2H11/2 and 4S3/2 (FIR(523/550)) are also investigated in detail. In the studied temperature range, the absolute sensitivity of FIR(523/550) monotonously increases with the rising temperature and reaches its maximum value 0.31% K-1 at 573 K. All the results imply that BaY2O4:Yb3+/Er3+ is a promising candidate for deep-tissue optical thermometry with high sensitivity.

Single band of red upconverison emission in Ce-based glass ceramics for light manipulation

Herein, single band of red upconversion (UC) emission in CeF3 nanostructured glass ceramics (GCs) is reported. CeF3 nanocrystals (NCs) were in-situ precipitated in aluminosilicate glass matrix, which was fabricated via quench-melting method and subsequent glass crystallization. Structural and spectrographic characterizations were also performed to verify the precipitation of CeF3 NCs and the partition of dopants. Ho3+ and Er3+ were elaborately selected to examine the cross relaxation (CR) process in Ce-based materials due to their ladder-like energy levels and similar energy gaps with Ce3+. Ultimately, single band of red UC emission was overtly observed independent of Ho3+ content, while a bit of green emission still stubbornly remained together with predominate red emission in Er3+ doped CeF3 NCs owing to the relative mismatch of energy gaps. Particularly, these results suggest that Ce-based materials are of importance in tailoring UC emissions, which could be a vital step toward realization of light manipulation for desirable emission.

Construction of self-sensitized LiErF4: 0.5% Tm3+@LiYF4 upconversion nanoprobe for trace water sensing

LiErF4 was commonly used as a dipolar-coupled antiferromagnet, and was rarely considered as a luminescent material. Herein, we achieved the strong red upconversion emission of LiErF4 simply by an inert shell coating, i.e., LiErF4@LiYF4. Owing to the unique and intrinsic ladder-like energy levels of Er3+ ions, this LiErF4 core-shell nanostructures present red emission (∼ 650 nm) under multi-band excitation in the near-infrared (NIR) region (∼ 808, ∼ 980, and ∼ 1,530 nm). A brighter and monochromic red emission can be further obtained via doping 0.5% Tm3+ into the LiErF4 core, i.e., LiErF4: 0.5% Tm3+@LiYF4. The enriched Er3+ ions and strong monochromic red emission natures make LiErF4: 0.5% Tm3+@LiYF4 nanocrystals very sensitive for trace water probing in organic solvents with detection limit of 30 ppm in acetonitrile, 50 ppm in dimethyl sulfoxide (DMSO), and 58 ppm in N, N-dimethylformamide (DMF) under excitation of 808 nm. Due to their superior chemical and physical stability, these nanoprobes exhibit excellent antijamming ability and recyclability, offering them suitable for real-time and long-term water monitoring.

Biodegradable Inorganic Upconversion Nanocrystals for In Vivo Applications.

Lanthanide-doped inorganic upconversion nanocrystals (UCNCs) are promising as fluorescent diagnostic and therapeutic agents for in vivo applications ranging from biological imaging to disease theranostics. However, all currently available lanthanide-doped inorganic UCNCs are not biodegradable and thus cannot be harmlessly eliminated from the body of living organism during a reasonable period of time, making their clinical translations nearly impossible. Here, we report a class of red-emitting biodegradable UCNCs based on Yb3+/Er3+-doped inorganic potassium heptafluozirconate (K3ZrF7:Yb/Er) that features a dynamically "soft" crystal lattice containing water-soluble [ZrF7]3- cluster and a K+ cation. The red-emitting K3ZrF7:Yb/Er UCNCs exhibit a pH-dependent biodegradation capability upon exposure to water both in vitro and in vivo, and the rapid biodegradation rate, monitored using the intrinsic red upconversion luminescence, can be tuned particularly in a mild acidic tumor microenvironment (pH ∼5-6). More importantly, the final biodegradation products of K3ZrF7:Yb/Er UCNCs can be excreted from the body of mice in a short period of time with no evidence of toxicity, in stark contrast to the nondegradable β-NaYF4:Yb/Er UCNCs that primarily accumulate in the main organs of mice. These findings described here unambiguously would benefit the future biomedical applications and clinical translations of lanthanide-doped inorganic UCNCs.

Photon quantification in Ho3+/Yb3+ co-doped opto-thermal sensitive fluotellurite glass phosphor.

Multi-photon-excited thermal-correlated green and red upconversion (UC) emissions have been quantified in Ho3+/Yb3+ co-doped fluotellurite (BZLFT) glass phosphor under the 978 nm laser excitation. The temperature dependence of the fluorescence intensity ratio (FIR) originated from UC emissions bands centered at 550 nm and 661 nm has been verified in the range of 303-543 K. The net emission photon numbers of 5F4+5S2→5I8 and 5F5→5I8 transition emissions are up to 40.08×1012 and 68.51×1012cps in the 0.4wt.%Ho2O3-0.4wt.%Yb2O3 co-doped BZLFT case under the 6.95W/mm2 laser power density. Furthermore, the quantum yield (QY) and luminous flux are determined to be dependent on pumping power. When the excitation power increases 874 mW, the QY values for 550 nm and 661 nm emissions are as high as 0.94×10-5 and 1.60×10-5. In addition, the high photon producing efficiency is conducive to ensuring high feedback to thermosensitive performance. The temperature thermal sensor can be manipulated steadily in medium temperature range, and the relative sensitivity reaches 0.4%K-1 at 303 K, which is 1 order of magnitude larger than those in several rare-earth-doped materials. Efficient photon conversion ability and high temperature sensitivity indicate that the rare-earth-ion-doped fluotellurite material has a prospective application in the construction of optical temperature sensors based on the FIR technique allowing for self-referenced temperature determination.

Reverse microemulsion synthesis of mixed α and β phase NaYF4:Yb,Er nanoparticles: calcination induced phase formation, morphology, and upconversion emission

A novel “water-in-oil” type reverse microemulsion assisted synthesis detail on the formation of mixed cubic and hexagonal (α + β) phase NaYF4:Yb,Er nanoparticles and their upconversion emission properties are presented. The effect of surfactants, fluorine precursors on the crystallographic phase fraction, crystallite size of NaYF4:Yb,Er nanoparticles on red upconversion emission is discussed. The NaYF4:Yb,Er nanoparticles synthesized with CTAB, and oleic acid surfactants give larger crystallite size and moderate hexagonal/cubic phase fraction. It has resulted very intense upconversion red emission. The oleic-acid-free preparation of NaYF4:Yb,Er nanoparticles resulted highly-agglomerated nanoparticles and low crystallite size, which gives less-intense upconversion emission. The cubic and hexagonal phase fractions of NaYF4:Yb,Er depends on surfactants, microemulsion, molar concentrations of precursors, and post-calcination. All these factors influence the mondispersibility and upconversion red emission properties. The 980 nm laser pump power dependent upconversion emission studies have confirmed the typical two-photon behavior in α + β phase NaYF4:Yb,Er nanoparticles. Their decay life was also measured to correlate the upconversion red emission intensity. The effect of mixed α + β phase NaYF4:Yb,Er nanoparticles on the 1530 nm NIR emission is also presented.

Up-conversion Luminescence and Temperature Sensing Properties of CaBi4Ti4O15:Tm3+, Yb3+ Ceramics

Tm3+/Yb3+ co-doped CaBi4Ti4O15 (CBT) bismuth layer structured ferroelectric ceramics were synthesized by a solid state reaction method and their microstructural and up-conversion (UC) luminescence properties were studied. Under 980-nm laser excitation, a strong blue light (475 nm) and a weaker red (650 nm) UC emission band were obtained, in which a three-photon UC mechanism is dominant, contributing to the transitions of 1G4 → 3H6, and 1G4 → 3F4. The optimal UC emission intensity was observed in the CBT: 0.005Tm3+/0.04Yb3+ samples. The transition 1G4 → (3H6, 3F4) of Tm3+ indicated a temperature-dependent behavior in the 163–503 K range. The maximum sensitivity was found to be 0.016 K−1 at 503 K based on the blue and red emissions. This indicates that CBT: 0.005Tm3+/0.04Yb3+ ferroelectric ceramics have great potential for applications in optical temperature sensors.

Fabrication of highly transparent Er3+, Yb3+:Y2O3 ceramics with La2O3/ZrO2 as sintering additives and the near-infrared and upconversion luminescence properties

Abstract Highly transparent Er3+, Yb3+:Y2O3 ceramics were fabricated by pressureless vacuum sintering method using La2O3 and ZrO2 as compound sintering additives. The microstructure, optical transmittance, upconversion and near-infrared spectral properties of the ceramics were investigated by X-ray diffraction, scanning electron microscopy, energy-dispersive spectrometry and spectroscopic analysis methods. The sintered ceramics displayed a pure cubic Y2O3 phase structure and a nearly pore-free microstructure with homogeneous grain morphology and grain-size distribution. The highest transmittance of Er3+, Yb3+:Y2O3 ceramics sintered at 1800 °C for 14 h with 9 at% of La2O3 and 3 at% of ZrO2 as compound additives was more than 82% in the range of 380–3000 nm. Under 980 nm wavelength excitation, the ceramics exhibited intense blue, green and red upconversion emission, and broad-bandwidth near-infrared emission centered at 1536 nm, which gives it the potential to act as a high-performance solid-state 1.54 μm near-infrared and upconversion laser gain media.

Synthesis, structural analysis, upconversion luminescence and magnetic properties of Ho3+/Yb3+ co-doped GdVO4 nanophosphor

Herein, we report a magneto-luminescent nanoparticle (NPs) GdVO4: Ho3+, Yb3+ which is paramagnetic in nature and can emit red emission under NIR excitation. Such magneto-luminescent material may serve potentially as a bi-functional probe (optical/magnetic) for bio-imaging applications. Material has been synthesized using a facile sol-gel technique. The structure and morphology of the synthesized NPs were investigated employing X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy techniques. Co-doped GdVO4 NPs crystalizes into tetragonal crystal structure with space group I41/amd. Nonlinear photon upconversion properties of co-doped materials were studied under 980 nm NIR laser excitation. The intense upconversion emission peaks arise at ~543 nm and ~653 nm due to electronic transition (5S2→ 5I8) and (5I5→5I8) of Ho3+, respectively and Yb3+ act as the sensitizer. Optimized concentration i.e. 1 mol% Ho3+/10 mol% Yb3+ gives prominent red emission. From the laser input power dependence studies, three-photon involvements were observed for the green and red bands. A possible mechanism for energy transfer and for possible transitions is also suggested and discussed in details using an energy level diagram. In addition to the excellent optical emission, the NPs show paramagnetic behaviour as well which was confirmed by vibrating sample magnetometer (VSM) studies. Since the prepared nano phosphor materials show the brilliant red upconversion emission under NIR excitation. This may be useful in red color emitter in the display such as LEDs and in bioimaging of the biomolecules. Also, Gd3+ based host gives its paramagnetic character which further promotes its utility in MRI applications.

Highly stable green and red up-conversion of LiYF4:Yb3+,Ho3+ for potential application in fluorescent labeling

The development of novel phosphors with stable and efficient green and red up-conversion (UC) emission is important for many applications such as fluorescent labeling, color display and anticounterfeiting. In this work, we report a stable and efficient green and red up-converter of LiYF4:Yb3+,Ho3+ octahedrons obtained by modified hydrothermal method. The UC emission and luminescence decays of LiYF4:Yb3+,Ho3+ with various Yb3+ and Ho3+ ion concentrations were studied systematically under 976 nm LD excitation. The Yb3+ and Ho3+ ion concentrations were optimized to be 20 mol% and 1 mol% respectively, for efficient green and red UC emissions. LiYF4:Yb3+,Ho3+ presents not only controlled morphology of monodisperse octahedrons with length of ∼20 μm and width of ∼10 μm, but also performs efficient green and red UC emissions, which is about four times stronger than that of β-NaGdF4: 20 Yb3+,0.5Ho3+ (NaGdF4: 20 Yb3+,0.5Ho3+). More importantly, the stable UC emission with variation of green intensity ratio ΔG% (G% = I520-570nm/I500-700nm, ΔG%= (G%)max-(G%)min) and red intensity ratio ΔR% (R% = I625-685nm/I500-700nm, ΔR%= (R%)max-(R%)min) < 1% was found over 976 nm LD excitation power density (PD) ranging from 1.0 to 5.6 W/cm2. Whereas, their variations of ∼6% and 25% are observed at the same excitation PD for NaGdF4:20 Yb3+,0.5Ho3+ and commercial β-NaYF4:20 Yb3+,2Er3+ (NaYF4: 20 Yb3+,2Er3+), respectively. The mechanism of green and red UC emissions in LiYF4: Yb3+,Ho3+ as a consequence of energy transfer processes has been briefly discussed taking into account the UC emission kinetics. The highly stable intensity ratio of G% and R% combined with the efficient green UC color hints the potential application of LiYF4: Yb3+,Ho3+ in fluorescent labeling and color display.

Self-monitored biological nanoheaters operating in the first biological window based on single-band red upconversion nanoparticles fabricated through architectural design

Abstract Achieving controllable heating in deep tissue is of vital importance for photothermal therapies. In this work, we developed single-band red upconversion (UC) nanoparticles (NPs) as self-monitored photothermal probes. The excitation (∼800 nm) and emission (∼652 nm) of the developed UCNPs are both located in the first biological window (I-BW), reducing the optical energy dissipation caused by biological tissue. The emission spectroscopic characteristics of these UCNPs were investigated, as well as their corresponding UC mechanisms. Moreover, the light-to-heat efficiency of the UCNPs reached 40%, and the self-monitored temperature feedback was demonstrated using the highly efficient red emission. The proposed UCNPs can deepen the penetration and avoid overheating in biological tissues if used in photothermal therapies. We consider that these characteristics will favour their use as in vivo photothermal probes with feedback provided by their emission of light.

Effect of Yb3+ codopant on the upconversion and thermoluminescent emission of Sr2CeO4:Er3+, Yb3+ phosphors

This work presents the structural, morphological, upconversion luminescence and Thermoluminescence properties of Sr2CeO4:Er3+,Yb3+ (SCO:Er, Yb) phosphors synthesized by a simple combustion method. The X-ray diffraction technique revealed that all the samples maintained their orthorhombic phase even for Yb concentrations as high as 12 mol%. Moreover, the morphological analysis by scanning electron microscopy (SEM) pointed out that SCO microparticles with sizes in the range of 0.2 μm–7.2 μm were obtained in samples doped with 0–3 mol% of Yb, but coalesced microparticles were observed for Yb concentrations from 7 to 12 mol%. The luminescence measurements demonstrated that the SCO: Er, Yb microparticles produced red and green upconversion emission bands and the red component increases with the Yb concentration. Also, the TL signals were recorded after solar/UV irradiation and found TL emission bands in the range of 60–150 °C and 150–350 °C. The traps responsible of the TL emissions were the oxygen vacancies.

Temperature sensitivity based on Er3+ fluorescence fluctuation in Gd2Ti2O7: Er3+-Yb3+ porous nanofibers

Abstract (Gd1−x−yErxYby)2Ti2O7 (GTOEY) fibers were synthesized by electrospinning technique and heat-treatment processes, in which nano-scale fibers vested with homogeneous porous morphology, high crystallinity and elevated temperature heat-resistance. Under 977 nm laser excitation, GTOEY nanofibers exhibit effective frequency upconversion (UC) fluorescence, therefore, the violent green and dimmed red UC emissions are identified as two-photon absorption processes, attributing to 2H11/2/4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 radiation transitions of Er3+, respectively. Moreover, the temperature sensitivity based on UC emission fluctuation of Er3+ over a wide temperature range of 303–633 K has been derived. Thereby, having used a 980 nm laser and achieved green UC luminescence of GTOEY fibers centered at 525 and 545 nm, the maximum absolute and relative sensitivity values are obtained to be 0.382% K−1 and 1.12% K−1, respectively. These significant results demonstrate that the GTOEY nanofibers with distinct porous structure and admirable photothermal sensitivities can be regarded as a promising temperature sensing material used for overheating alarm and safety protection equipment.