Currently, the major commercial white light‐emitting diode (WLED) is the phosphor‐converted LED made of the InGaN blue‐emitting chip and the Ce3+:Y3Al5O12 (Ce:YAG) yellow phosphor dispersed in organic epoxy resin or silicone. However, the organic binder in high‐power WLED may age easily and turn yellow due to the accumulated heat emitted from the chip, which adversely affects the WLED properties such as luminous efficacy and color coordination, and therefore reduces its long‐term reliability as well as lifetime. Herein, an innovative luminescent material: transparent Ce:YAG phosphor‐in‐glass (PiG) inorganic color converter, is developed to replace the conventional resin/silicone‐based phosphor converter for the construction of high‐power WLED. The PiG‐based WLED exhibits not only excellent heat‐resistance and humidity‐resistance characteristics, but also superior optical performances with a luminous efficacy of 124 lm/W, a correlated color temperature of 6674 K and a color rendering index of 70. This easy fabrication, low‐cost and long‐lifetime WLED is expected to be a new‐generation indoor/outdoor high‐power lighting source.

New non-rare-earth-based oxide red phosphor discovery is of great interest in the field of energy-efficient LED lighting. In this work, a novel blue-light activated CaMg2Al16O27:Mn(4+) (CMA:Mn(4+)) phosphor, showing strong red emission peaked at ∼655 nm under 468 nm excitation, is prepared by a solid-state reaction route. The microstructure and luminescent performance of this red-emitting phosphor are investigated in detail with the aids of X-ray diffraction refinement, diffuse reflection spectra, steady-state photoluminescence spectra and temperature-dependent PL/decay measurements. The crystal field strength (Dq) and the Racah parameters (B and C) are carefully calculated to evaluate the nephelauxetic effect of Mn(4+) suffering from the CMA host. After incorporating CMA:Mn(4+) and YAG:Ce(3+) phosphor microcrystals into the glass host via a "phosphor-in-glass (PiG)" approach, warm white-light is achieved in the assembled high-powered w-LED device, thanks to the improved correlated color temperature and color rendering index.

3139wileyonlinelibrary.com discriminable emission peaks as the monitored signals, and to suppress absolute and relative detecting errors, high absolute and relative temperature sensitivities are required.In this aspect, conventional investigations focus on the thermally coupled level pairs (TCL) of rare earth ions (for example, 2 H 11/2 and 4 S 3/2 level for Er 3+). [7][8][9][10][11][12][13][14][15] Typically, with variation of temperature, population in the upper and lower levels of TCL would change oppositely, inducing variation in FIR of these two levels. For this type of temperature sensing materials, a narrow energy gap between TCL would favor the absolute temperature sensitivity ( S a ), but be harmful to the relative temperature sensitivity ( S r ). In addition, the narrow energy gap would induce overlap of the two monitored emission peaks, resulting in an inferior signal discriminability. [ 9,12 ] In contract, a wide energy gap between TCL would benefi t S r and the signal discriminability, but weaken the thermal coupling of TCL, leading to a low S a . [ 13,15 ] Generally speaking, in the TCL-based optical thermometry, simultaneously promoting S a , S r and signal discriminability is almost impossible.Other kinds of thermometry strategy have also been introduced into the optical thermometric technique. For example, the phonon assisted energy transfer between Eu 3+ and Tb 3+ ions has been utilized in optical thermometry. [16][17][18][19] However, this kind of thermometry is usually applicable only at temperature below 320 K. Nanocomposites containing quantum dots and rare earth ions have also been applied as thermometric materials relying on the different thermal quenching behaviors of quantum dots and rare earth ions. [ 20,21 ] However, FIR of these materials is easily infl uenced by other environment parameters (such as pH value), which would introduce error in temperature detection. Apparently, searching for new thermometry strategy to develop high-performance luminescent temperature sensing materials is highly desired.In previous studies, the metal-to-metal intervalence charge transfer (IVCT) processes between lanthanide (Pr 3+ or Tb 3+ ) and d 0 electron confi gured transition metal ions (Ti 4+ , V 5+ , Nb 5+ , Mo 6+ , or W 6+ ) in oxide crystals have been demonstrated to be an effective pathway to excite the corresponding lanthanide ions. [22][23][24][25][26] Moreover, IVCT can provide an effi cient quenching A Novel Optical Thermometry Strategy Based on Diverse Thermal Response from Two Intervalence Charge Transfer StatesYan Gao , Feng Huang , * Hang Lin , Jiangcong Zhou , Ju Xu , and Yuansheng Wang * In this work, a novel thermometry strategy based on the diversity in thermal quenching behavior of two intervalence charge transfer (IVCT) states in oxide crystals is proposed, which provides a promising route to design selfreferencing optical temperature sensing material with superior temperature sensitivity and signal discriminability.

With the technological advancements of high‐quality lightings and high‐end displays, white light‐emitting‐diodes (w‐LEDs) are quickly developing towards high energy density excitation, high output power and high device stability, which requires outstanding thermal properties of the phosphor color converters. In this connection, all‐inorganic luminescent glass ceramic (GC), exhibiting excellent physical/chemical stability to address the serious aging and yellowing issues of conventional phosphor/silicone composite, receives great attention recently and is regarded as a new generation color converter with longevity. Herein, a thorough survey of the research progress of this kind of material is made, with focus put on the design principle, microstructure‐property relationship, packaging technology and the burgeoning application direction. Some challenging issues are discussed and potential directions are suggested for further developing the phosphor‐glass composite fulfilling various requirements in practical application. This Review can promote rapid progress of long‐lifetime high‐power w‐LEDs.

Owing to its low cost and admirable luminescent characteristics for use in warm white-light-emitting diode (w-LED) applications, the non-rare-earth Mn4+-activated red phosphor has emerged as a potent competitor of commercial Eu2+-doped nitrides in recent years. In this work, the novel red-emitting phosphor BaMgAl10–2x O17:xMn4+,xMg2+ is successfully synthesized, which exhibits bright and narrow-band luminescence peaking at 660 nm with a full width at half-maximum of merely ∼30 nm upon blue light excitation. The unique structural feature of BMA, i.e., alternating arrangements of Mn4+-doped MgAl10O16/undoped BaO layers in the z direction and Mn4+-doped [AlO6]/undoped [AlO4] groups in the x–y plane, favors efficient Mn4+ luminescence by reducing nonradiative energy loss channels. Unlike previously reported hosts, BMA accommodates Mg2+ in the lattice without destabilizing the crystal structure. Remarkably, partitioning Mg2+ in the host not only greatly enhances Mn4+ luminescence by 1.84-fold but also retards the concentration quenching effect induced by Mn4+ dipole–dipole interactions owing to the reduced number of Mn4+–Mn4+–O2– pairs. Spectroscopy demonstrates that the luminescence of optimized BMA:0.02Mn4+,0.02Mg2+ exhibits a high color purity of 98.3%, good color stability against heat, and excellent resistance to thermal impact. When incorporating BMA:0.02Mn4+,0.02Mg2+ and YAG:Ce3+ phosphors into an oxide glass matrix at various ratios and then coupling the phosphor-in-glass color converters using a blue chip, the chromaticity parameters of the fabricated w-LED are well-tuned, with the correlated color temperature decreasing from 6608 to 3622 K and the color rendering index increasing from 68.4 to 86.0, meeting the requirements for in-door lighting use.

The launch of the big data era puts forward challenges for information preservation technology, both in storage capacity and security. Herein, a brand new optical storage medium, transparent glass ceramic (TGC) embedded with photostimulated LiGa 5 O 8 : Mn 2+ nanocrystals, capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode, is developed. The highly ordered nanostructure enables light-matter interaction with high encoding/decoding resolution and low bit error rate. Importantly, going beyond traditional 2D optical storage, the high transparency of the studied bulk medium makes 3D volumetric optical data storage (ODS) possible, which brings about the merits of expanded storage capacity and improved information security. Demonstration application confirmed the erasable-rewritable 3D storage of binary data and display items in TGC with intensity/ wavelength multiplexing. The present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media.

State-of-the-art progress in strategy design based on the Ln3+ luminescence involving dual emission construction for ratiometric luminescence thermometry is reviewed.

The high-powered alternating current (AC) light-emitting diode (LED) (AC-LED), featuring low cost, high energy utilization efficiency, and long service life, will become a new economic growth point in the field of semiconductor lighting. However, flicker of AC-LED in the AC cycles is not healthy for human eyes, and therefore need to be restrained. Herein we report an innovation of persistent "phosphor-in-glass" (PiG) for the remote-type AC-LED, whose afterglow can be efficiently activated by the blue light. It is experimentally demonstrated that the afterglow decay of PiG in the microsecond range can partly compensate the AC time gap. Moreover, the substitution of inorganic glass for organic resins or silicones as the encapsulants would bring out several technological benefits to AC-LED, such as good heat-dissipation, low glare, and excellent physical/chemical stability.