Extrinsic photoluminescence properties of individual micro-particle of Cs4PbBr6 perovskite with "defect" structure.

Optical performance of the lead halide perovskites with zero-dimension (0D) structure has been in a hot debate for optoelectronic applications. Here, Cs4PbBr6 hexagonal micro-particles with a remarkable green emission are first fabricated via a low-temperature solution-process employed ethanol as solvent. Our results underline that the existence of bromine vacancies and the introduction of hydroxyl induce a narrowed band gap with the formation of a defect level, which contributes to the extrinsic photoluminescence (PL) properties synergistically. Thanks to the high exciton binding energy and the unique morphology with a regular geometric structure of the as-obtained micro-particles, two-photon pumped amplified spontaneous emission (ASE) and single mode lasing from an individual Cs4PbBr6 particle are realized. Our results not only provide an insight into the origin of optical emission from Cs4PbBr6, but also demonstrate that the versatile Cs4PbBr6 offers a new opportunity for novel nonlinear photonics applications as an up-conversion laser.

Phase transformation induced reversible modulation of upconversion luminescence of WO3:Yb3+, Er3+ phosphor for switching devices.

The upconverting luminescence properties of phosphors are dependent on the hosts. In this work, the WO3:Yb3+, Er3+ phosphor was prepared, and the reversible phase transformation from the WO3 to the WO2 was obtained by alternating the sintering in a reducing atmosphere or in air. The influence of reversible phase transformation on the upconversion luminescence was investigated first. The WO3:Yb3+, Er3+ phosphor exhibits the visible upconversion luminescence, while no upconversion luminescence was observed in the WO2:Yb3+, Er3+ phosphor. The reversible modulation of upconversion luminescence of the WO3:Yb3+, Er3+ phosphor retains the excellent reproducibility, exhibiting the potential applications in data storage and optical switches.

Effect of Defect Distribution on the Optical Storage Properties of Strontium Gallates with a Low-Dimensional Chain Structure.

The low-dimensional structure of the SrGa2O4 host exhibits a self-activated long persistent luminescence related to the creation of the oxygen vacancies. Because of the unique structure of the SrGa2O4 with a chain of cations along the a crystal direction, the emission and trapping centers could be introduced easily when the metal ions of Bi(3+) are doped. Both the photoluminescence and long persistent luminescence are related to two efficient emission centers of Bi(3+) in the two different crystallographic Sr sites, while the photostimulated luminescence spectra exhibit only one emission center of Bi1 ions under excitation at 980 or 808 nm. The results indicate that the distribution of defects in the low-chain structure of the SrGa2O4 host plays a vital role in the capture and transfer processes of carriers, which has a profound influence on the luminescence performance of SrGa2O4:Bi(3+) as one of the electron-trapping materials.

Self-activated long persistent luminescence from different trapping centers of calcium germanate.

Ca2Ge7O16 phosphor with a self-activated LPL was synthesized. The unique emission of Ca2Ge7O16 related to the creation of the oxygen vacancies was proved. With increasing concentration of Nd3+, the LPL peaks in these phosphors red-shift obviously, which results in the corresponding emitting color changing from purple to blue. The thermoluminescence spectra indicate that there are two different types of traps, which are attributed to oxygen and calcium vacancies, respectively. Both of them not only act as the trapping centers, but also as the exciton energy-level involved in the emission process. Accordingly, the mechanism of the LPL process was discussed briefly.

Sunlight activated long-lasting luminescence from Ba5Si8O21: Eu(2+),Dy(3+) phosphor.

Visible-light persistent phosphors are commonly used as self-sustained night vision and fluorescence labeling materials. From the inspiration of the structure of six-membered rings plane in Ba4(Si3O8)2, a similar structure of Ba5Si8O21 is expected that could exhibit more excellent phosphorescence property. In this Article, we report a novel visible long-lasting luminescence phosphor of Eu(2+)/Dy(3+) codoped Ba5Si8O21 for the first time. Ba5Si8O21:Eu(2+),Dy(3+) phosphor could be activated effectively by sunlight or even in severe weather conditions, which is mainly attributed to the broad excitation spectrum (200-455 nm) and highly responds to UV-A and violet-light in the solar spectrum. After activation, Ba5Si8O21:Eu(2+),Dy(3+) emits intense emission at 380-680 nm with persistent phosphorescence beyond 16 h. Moreover, it exhibits excellent and stable phosphorescence even in water, indicating that Ba5Si8O21:Eu(2+),Dy(3+) will be a all-weather material that can be effectively and repeatedly charged by natural daylight in all kinds of open-air environments. Furthermore, the quantum tunneling behavior was illustrated in the afterglow mechanism.

Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

YPO4: Tm, Yb inverse opal photonic crystals were successfully synthesized by the colloidal crystal templates method, and the visible-infrared quantum cutting (QC) photoluminescence properties of YPO4: Tm, Yb inverse opal photonic crystals were investigated. We obtained tetragonal phase YPO4 in all the samples when the samples sintered at 950°C for 5 h. The visible emission intensity of Tm3+ decreased significantly when the photonic bandgap was located at 650 nm under 480 nm excitation. On the contrary, the QC emission intensity of Yb3+ was enhanced as compared with the no photonic bandgap sample. When the photonic bandgap was located at 480 nm, the Yb3+ and Tm3+ light-emitting intensity weakened at the same time. We demonstrated that the energy transfer between Tm3+ and Yb3+ is enhanced by the suppression of the red emission of Tm3+. Additionally, the mechanisms for the influence of the photonic bandgap on the energy transfer process of the Tm3+, Yb3+ codoped YPO4 inverse opal are discussed.

Treatment-influenced associations of PML-RARα mutations, FLT3 mutations, and additional chromosome abnormalities in relapsed acute promyelocytic leukemia.

Mutations in the all-trans retinoic acid (ATRA)-targeted ligand binding domain of PML-RARα (PRα/LBD+) have been implicated in the passive selection of ATRA-resistant acute promyelocytic leukemia clones leading to disease relapse. Among 45 relapse patients from the ATRA/chemotherapy arm of intergroup protocol C9710, 18 patients harbored PRα/LBD+ (40%), 7 of whom (39%) relapsed Off-ATRA selection pressure, suggesting a possible active role of PRα/LBD+. Of 41 relapse patients coanalyzed, 15 (37%) had FMS-related tyrosine kinase 3 internal tandem duplication mutations (FLT3-ITD+), which were differentially associated with PRα/LBD+ depending on ATRA treatment status at relapse: positively, On-ATRA; negatively, Off-ATRA. Thirteen of 21 patients (62%) had additional chromosome abnormalities (ACAs); all coanalyzed PRα/LBD mutant patients who relapsed off-ATRA (n = 5) had associated ACA. After relapse Off-ATRA, ACA and FLT3-ITD+ were negatively associated and were oppositely associated with presenting white blood count and PML-RARα type: ACA, low, L-isoform; FLT3-ITD+, high, S-isoform. These exploratory results suggest that differing PRα/LBD+ activities may interact with FLT3-ITD+ or ACA, that FLT3-ITD+ and ACA are associated with different intrinsic disease progression pathways manifest at relapse Off-ATRA, and that these different pathways may be short-circuited by ATRA-selectable defects at relapse On-ATRA. ACA and certain PRα/LBD+ were also associated with reduced postrelapse survival.

Enhancement of near-infrared to near-infrared upconversion emission in the CeO2: Er³âº, Tm³âº, Yb³âº inverse opals.

In this Letter, CeO2: Er³âº, Tm³âº, Yb³âº inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO2: Er³âº, Tm³âº, Yb³âº inverse opals.

Preparation and upconversion emission modification of Yb, Er co-doped Y2SiO5 inverse opal photonic crystals.

Yb, Er co-doped Y2SiO5 inverse opal photonic crystals with three-dimensionally ordered macroporous were fabricated using polystyrene colloidal crystals as the template. Under 980 nm excitation, the effect of the photonic stopband on the upconversion luminescence of Er3+ ions has been investigated in the Y2SiO5:Yb, Er inverse opals. Significant suppression of the green or red UC emissions was detected if the photonic band-gap overlaps with the Er3+ ions emission band.

Enhancement of the short wavelength upconversion emission in inverse opal photonic crystals.

Upconversion luminescence properties of Yb-Tb codoped Bi4Ti3O12 inverse opals have been investigated. The results show that the upconversion emission can be modulated by the photonic band gap. More significantly, in the upconversion inverse opals, the excited-state absorption of Tb3+ is greatly enhanced by the suppression of upconversion spontaneous emissions of the intermediate excited state, and thus the short wavelength upconversion emission from Tb3+ is considerably improved. We believe that the present work will be valuable for not only the foundational study of upconversion emission modifications but also new optical devices in upconversion displays and short wavelength upconversion lasers.

Alpha-NaYF4:Nd3+ nanocrystal with near-infrared to near-infrared luminescence for bioimaging applications.

Nd3+ doped alpha-NaYF4 nanocrystals with size of about 15 nm were successfully synthesized through hydrothermal method. Nearly pure near-infrared to near-infrared (NIR-to-NIR) luminescence can be realized. Moreover, the excitation and the emission at 880 and 1060 nm, respectively, are away from the visible region. These are beneficial to deeper tissue penetration and reduced auto-fluorescence. This material exhibits an excellent NIR-to-NIR emission performance and is thus potentially applicable as a high-contrast in vitro and in vivo imaging probe.

[Preparation and up-conversion luminescence properties of Yb3+/Tm3+ co-doped Sb2O4 powder].

The Sb2O4:Yb3+, Tm3+ up-conversion luminescence powder with excellent physical, chemical stability and relative low phonon energy was synthesized by the high temperature solid-state reaction and its up-conversion luminescence property was investigated. Under the 980 nm excitation, infrared and blue up-conversion emissions centered at 800 and 480 nm were observed, which were assigned to the 1G4-->3H6 and 3H4-->3 He transitions of Tm2+, respectively. The influence of Yb3+ and Tm3+ concentration on the up-conversion emission property was also obtained. The up-conversion luminescence increases with increasing of Yb3+ and Tm3+ concentration. Additionally, the up-conversion luminescence mechanism was discussed based on the dependence of Tm3+ up-conversion luminescence on pump power. It is interesting that two photon excitation processes for blue and infrared emission were observed in the Sb2O04: Yb3+, Tm3+ powder under a 980 nm excitation. Based on the energy level diagram of Tma3 and Yb2+ ions, we think that two photons blue emission is contributed to the cooperation energy transfer between Tm"+ and Yb3+ ions. We believe that the Sbz04 : Yb3 , Tm2+ up-conversion luminescence powder will have potential application for new optical devices in up-conversion color displays, sensors, detection of infrared radiation, and lasers.

Enhancement of Upconversion Luminescence through Three-Dimensional Design of Plasma Ti3O5-Coupled Structural Domain-Limiting Effects.

Upconversion luminescence plays a crucial role in various technological applications, and among the various valence states of lanthanide elements, Ln3+ has the highest stability. The 4f orbitals of these elements are in a fully empty, semifull, or full state. This special 4f electron configuration allows them to exhibit rich discrete energy levels. However, the 4f-4f transition of Ln3+ rare earth ions itself is prohibited, resulting in a lower luminescence efficiency. This limitation greatly hinders the practical application of upconversion luminescence. In this study, we report nanostructured luminescence-enhanced substrate platforms with both semiconductive local surface plasmons and spatially confined domain effects on a single defect semiconductor substrate. By coupling NaYF4:Yb-Er nanoparticle emitters to the surface of Ti3O5 NC-arrays plasmonic nanostructures, an ultrabright luminescence with a 32-fold increase in green emission and a 40-fold increase in red emission was achieved. Furthermore, the fluorescence resonance energy transfer characteristics observed in the R6G/NaYF4/Ti3O5 NC-array composite film enable accurate detection of fluorescent molecules. The results provide an innovative and intelligent approach to enhance the upconversion luminescence intensity of rare-doped nanoparticles and develop highly sensitive molecular detection systems based on the above luminescence enhancement.

Investigation of upconversion and near infrared emission properties in CeO2: Er³âº, Yb³âº inverse opals.

The upconversion emission of rare earth ions can be modified in photonic crystals, however, the influence of upconversion emission modification of rare earths on near infrared emission has not been investigated yet in the photonic crystals. In the paper, CeO2: Er³âº, Yb³âº inverse opals with the photonic band gaps at 545, 680 and 450 nm were prepared by polystyrene colloidal crystal templates. The upconversion and the near infrared emission properties of Er³âº ions were systematically investigated in the CeO2: Er³âº, Yb³âº inverse opals. Comparing with the reference sample, significant suppression of both the green and red upconversion luminescence of Er³âº ions were observed in the inverse opals. It is interesting that the infrared emission located at 1,560 nm was enhanced due to inhibition of upconversion emission in the inverse opals. Additionally, mechanism of upconversion emission of the inverse opal was discussed. The photon avalanche upconversion process is observed.

Significant enhancement of Sm3+ photoreduction in halide nanophase precipitated AIF3-based glasses under femtosecond laser irradiation.

The electronegativity effect for the efficient photoreduction of Sm3+ to Sm2+ in Br-modified fluoroaluminate glasses was investigated after femtosecond laser (fs) irradiation. Sm2+ luminescence was strongly observed in the higher Br-modified samples, and basing on the TEM and DSC measurements, BaBr2 nanophases were precipitated from the glass matrix in the laser focused areas. From the EDS spectra, it was found that Sm3+ can be selectively incorporated into the BaBr2 nanophases. More electrons provided by the nanophase facilitated the Sm3+ reduction in the irradiation process. Since the photoreduction efficiency of Sm3+ in Br-modified glass is evidently higher than that in Cl-modified glasses, the effect of halide ions electronegativity on Sm3+ photoreduction was identified and relevant mechanism was discussed.

[Synthesis and photoluminescence properties of Eu3+, Bi3+ codoped BaZrO3 phosphors].

The BaZrO3 : 0.05Bi, xEu(x = 0, 0.010, 0.025, 0.050) phosphors were prepared by using high-temperature solid-state reaction in reducing atmosphere, and their photoluminescence properties were investigated. The broadband emission peak of Bi3+ and the typical emission peaks of Eu3+ were observed in the BaZrO3 phosphors co-doped with Bi3+ and Eu3+ under 340 nm excitation. It is confirmed that energy transfer occurred between Bi3+ and Eu3+ in the BaZrO3 : Bi, Eu phosphors, and the white light BaZrO3 phosphors can be obtained through the energy transfer between Bi3+ and Eu3+.

Engineering CsPbX3 (X = Cl, Br, I) Quantum Dot-Embedded Borosilicate Glass through Self-Crystallization Facilitated by NaF as a Phosphor for Full-Color Illumination and Laser-Driven Projection Displays.

All inorganic perovskite (CsPbX3, X = Cl, Br, I) quantum dot (QD) glass samples are considered the next generation of lighting materials for their excellent luminescence properties and stability, but crystallization conditions are difficult to control, which often leads to the inhomogeneous crystallinity of QDs. Here, we provided evidence that the presence of sodium fluoride induced self-crystallization of CsPbBr3 QDs during routine glass formation without the need for additional heat treatment. We showed that NaF simultaneously affected the network structure of glass and promoted the formation of CsPbBr3 QDs, that is, Na+ ions entered the glass network skeleton, partially interrupting the network structure, while the strong electronegativity of F- ions attracted Cs+ and Pb2+ ions into the gaps formed in the glass networks that had been loosened up by Na+ ions, which reduced the activation energy of crystallization processes. Our results showed that NaF-induced CsPbBr3 QDs glass had excellent thermal stability, high photoluminescence quantum efficiency (49%), and luminescent stability under high-power laser irradiation. Finally, this work also demonstrated the general applicability of this method in the making of a series of CsPbX3 (X = Cl, Br, I) QD glass samples by NaF-induced self-crystallization, which drastically expanded the color gamut to a range of full spectrum for luminescence and laser-driven projection displays. We believe that the work presented here represents a new direction for the research and development of full-color gamut inorganic perovskite quantum dot glass samples, which could have a significant impact on the future applications of laser-driven projection displays as well.

The effect of MnCO3 on the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and near-infrared emission bandwidth flatness of Er3+/Tm3+/Yb3+ co-doped barium zinc silicate glasses.

The roles of Mn2+ ions in the MnCO3 compound, leading to the formation of an Mn2+-Yb3+ dimer and affecting the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and near-infrared (NIR) emission bandwidth flatness of Er3+/Tm3+/Yb3+ co-doped in SiO2-ZnO-BaO (SZB) barium zinc silicate glasses, were investigated in this work. The composition of all elements from the original raw materials that exist in the host glasses was determined using energy-dispersive X-ray spectroscopy (EDS). Under the excitation of a 980 nm laser diode (LD), the NIR emission of Er3+/Tm3+/Yb3+-co-doped SZB glasses produced a bandwidth of about 430 nm covering the O, E, and C bands. The effects of Mn2+ ions and the Mn2+-Yb3+ dimer on the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and bandwidth flatness of NIR emission of Er3+/Tm3+-co-doped and Er3+/Tm3+/Yb3+-co-doped SZB glasses were also assigned. The optimal molar concentration of Mn2+ ions was determined such that the NIR bandwidth flatness of Er3+/Tm3+/Yb3+-co-doped SZB glasses was the flattest. In addition, the role of Mn2+ ions in reducing the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions was also calculated and discussed.

Optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses.

In this study, the indirect/direct optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses under different excitation wavelengths were investigated. Zinc calcium silicate glasses with the main compositions of SiO2-ZnO-CaF2-LaF3-TiO2 were prepared by the conventional melting method. EDS analysis was performed to determine the elemental composition existing in the zinc calcium silicate glasses. Visible (VIS)-, upconversion (UC)-, and near-infrared (NIR)-emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were also investigated. Indirect optical band gaps and direct optical band gaps of Bi m+-, Eu n+- single-doped, and Bi m+-Eu n+ co-doped SiO2-ZnO-CaF2-LaF3-TiO2-Bi2O3-EuF3-YbF3 zinc calcium silicate glasses were calculated and analyzed. CIE 1931(x, y) color coordinates for VIS and UC emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were determined. Besides, the mechanism of VIS-, UC-, NIR-emissions, and energy transfer (ET) processes between Bi m+ and Eu n+ ions were also proposed and discussed.

Lead-Free Double Perovskite Cs2NaErCl6: Li+ as High-Stability Anodes for Li-Ion Batteries.

Halide perovskite materials have been used in the field of lithium-ion batteries because of their excellent ion migration characteristics and defect tolerance. However, the current lead-based perovskites used for lithium-ion batteries are highly toxic, which may hinder the pace of further commercialization. Therefore, it is still necessary to develop a new type of stable and pollution-free perovskite anode material. Herein, we for the first time use a high-concentration lithium-ion doped rare-earth-based double perovskite Cs2NaErCl6:Li+ as the negative electrode material for a lithium-ion battery. Thanks to its excellent structure stability, the assembled battery also has high cycle stability, with a specific capacity of 120 mAh g-1 at 300 mA g-1 after 500 cycles with a Coulomb efficiency of nearly 100%. The introduction of a rare earth element in a lead-free double perovskite paves a new way for the development of novel promising anode materials in the field of lithium storage applications.