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The absorption and photoluminescence (PL) spectra of negatively photodoped ZnO nanocrystals dispersed in ethanol are measured under a stepwise photodoping process at room temperature. The spectra are measured almost simultaneously at each photodoping level and compared in detail to discuss the origin of the spectral change. The redshift of the PL spectrum and the increase of its intensity are clearly observed in the early stage of photodoping and are attributed to the trion luminescence. The PL spectrum is found to split into two peaks for highly photodoped nanocrystals. The cause of the splitting is discussed in terms of its dependence on the nanocrystal size. [ABSTRACT FROM AUTHOR]

Chiral perovskite materials are being extensively studied as one of the most promising candidates for circularly polarized luminescence (CPL)-related applications. Balancing chirality and photoluminescence (PL) properties is of great importance for enhancing the value of the dissymmetry factor (glum), and a higher glum value indicates better CPL. Chiral perovskite/quantum dot (QD) composites emerge as an effective strategy for overcoming the dilemma that achieving strong chirality and PL in chiral perovskite while at the same time achieving high glum in this composite is very crucial. Here, we choose diphenyl sulfoxide (DPSO) as an additive in the precursor solution of chiral perovskite to regulate the lattice distortion. How structural variation affects the chiral optoelectronic properties of the chiral perovskite has been further investigated. We find that chiral perovskite/CdSe–ZnS QD composites with strong CPL have been achieved, and the calculated maximum |glum| of the composites increased over one order of magnitude after solvent-additive modulation (1.55 × 10−3 for R-DMF/QDs, 1.58 × 10−2 for R-NMP-DPSO/QDs, −2.63 × 10−3 for S-DMF/QDs, and −2.65 × 10−2 for S-NMP-DPSO/QDs), even at room temperature. Our findings suggest that solvent-additive modulation can effectively regulate the lattice distortion of chiral perovskite, enhancing the value of glum for chiral perovskite/CdSe–ZnS QD composites. [ABSTRACT FROM AUTHOR]

Endohedrally doped clusters form a large category of cage clusters, with unique structures, diverse elemental compositions, and highly tunable electronic structures and physisochemical properties. They have been widely achieved in laboratory and may serve as functional building blocks for assembling new supermolecular structures and devices. In this paper, for the first time, we disclosed the luminescence properties of endohedrally doped group-IV clusters by time-dependent density functional theory calculations. A total of 64 cage clusters have been explored in terms of stability, emission wavelength, and the energy difference between the first excited singlet and triplet states. The key geometric and electronic factors governing the photophysical properties of these cage clusters were unveiled, to provide crucial insights for crafting atomically precise nanoclusters for optical and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion (UC) luminescent materials display multicolor emissions, making them ideal for a variety of applications, such as multi-channel biological imaging, fluorescence encryption, anti-counterfeiting, and 3D display. Manipulating the UC emissions of the luminescent materials with a fixed composition is crucial for their applications. Herein, we propose a facile strategy to achieve pulse-width-dependent multicolor UC emissions in NaYF4:Yb/Er/Tm nanocrystals. Upon excitation with a 980 nm continuous-wave laser diode, Er3+ ions in NaYF4:20%Yb,15%Er,1%Tm nanocrystals exhibited UC emissions with a red-to-green (R/G) ratio of 11.3. Nevertheless, by employing a 980 nm pulse laser with pulse widths from 0.1 to 10 ms, the UC R/G ratio can be easily adjusted from 0.9 to 11.3, resulting in continuous and remarkable color transformation from green, yellow, orange, to red. By virtue of the dynamic luminescence color variation of these NaYF4:20%Yb,15%Er,1%Tm nanocrystals, we demonstrated their potential applications in the areas of anti-counterfeiting and information encryption. These findings provide deep insights into the excited-state dynamics and energy transfer of Er3+ in NaYF4:Yb/Er/Tm nanocrystals upon 980 nm pulse excitation, which may pave the way for designing multicolor UC materials toward versatile applications. [ABSTRACT FROM AUTHOR]

This work reports analysis of the reverse-bias breakdown characteristics of homojunction gallium nitride (GaN) p–i–n (PIN) rectifiers fabricated on bulk GaN substrates. Sub-bandgap photoluminescence mapping at room temperature as a contactless, non-destructive wafer inspection method was performed to analyze the impact of material properties on grown GaN PIN diodes and to study the correlation between defect types and breakdown characteristics of vertical GaN PIN rectifiers. Under the sub-bandgap excitation, yellow luminescence is dominant. The premature breakdown characteristics of the fabricated kV-class vertical GaN PIN rectifiers with nitrogen-implanted floating guard rings are found to be associated with material defects and deep level complexes. Photoluminescence mapping has demonstrated its effectiveness in quantitative analysis of dislocations and other types of defects. [ABSTRACT FROM AUTHOR]

This article discusses a new fabrication process for colloidal silicon quantum dots (SiQDs) that allows for the tuning of their luminescence color from red to green. The process involves low-temperature thermal cracking of electrochemically prepared meso-porous silicon flakes in a mixture of 10-undecen-1-ol and aqueous hydrogen fluoride solution. The size of the SiQDs and their luminescence color can be controlled by adjusting the content of hydrogen fluoride. The article also explores the properties and potential applications of SiQDs in various fields, such as photovoltaic devices, light emitting devices, bio-imaging, and sensing. The document discusses the size-dependent radiative recombination processes of SiQDs, including factors that can affect their photoluminescence properties. It also explains the formation mechanisms of SiQDs and how they can result in different photoluminescence colors and peak wavelengths. The document concludes by discussing the relationship between the size of SiQDs and their photoluminescence peak energies, as well as the effect of surface passivation on quantum confinement. The article presents a novel method for producing SiQDs with tunable emission colors and suggests potential applications for SiQD devices. [Extracted from the article]

Glow-in-the-daylight is a fascinating luminescence phenomenon displayed by certain storage phosphors that emit ultraviolet light upon being stimulated by ambient lighting. In this study, we investigate the influence of indoor lighting on the glow-in-the-daylight emission of a co-doped garnet phosphor, Y3Al5O12:Pr3+,Eu3+, known for its deep trap that effectively retains energy. Our experimental results demonstrate an interesting observation that, following x-ray radiation at room temperature, this phosphor exhibits negligible persistent luminescence in darkness but emits intense ultraviolet light peaking at 318 nm under indoor lighting conditions. This emphasizes the crucial role played by ambient lighting in releasing stored energy. Our findings not only shed light on the influence of indoor illumination dose and spectral distribution on the persistently stimulated luminescence but also expand our exploration to various ultraviolet phosphors with deep traps, with the aim of uncovering novel materials applicable in glow-in-the-daylight scenarios. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (NCs) have superior luminescence properties compared to classical semiconductor NCs and they are considered promising materials for next-generation emitters. In this work, we measured the size and temperature dependence of the luminescence decay curve in CsPbBr 3 NCs. To reproduce the experimental results, a simple model including one and two-phonon transitions between the exciton fine structures is introduced. It is found that the temperature dependence of the decay rates in small NCs is better reproduced by the two-phonon model rather than by the one-phonon model. However, the one-phonon process becomes more important for large NCs as the bright-dark splitting decreases. [ABSTRACT FROM AUTHOR]

Modulation doping of silicon has great potential for miniaturization, surface passivation, and third generation photovoltaics (PV). At a modulation-doped silicon surface, we observe the formation of a 2D hole layer at the silicon surface at low temperatures by means of photoluminescence (PL) measurements. A line shape analysis of band–band and hot luminescence reveals the hole density (which is equal to the modulation-doped acceptor density). A high excitation intensity leads to a Fermi edge singularity of the band–band and hot PL emission. While the 2D layer can be characterized by the observed luminescence, the spectral region of twice the bandgap is fully dominated by emission from this surface layer, impeding the measurement of bulk hot luminescence, e.g., from Auger electrons or from nonthermalized carriers in a hot carrier PV device. [ABSTRACT FROM AUTHOR]

Modeling light–matter interactions in hybrid plasmonic materials is vital to their widening relevance from optoelectronics to photocatalysis. Here, we explore photoluminescence (PL) from ZnO nanorods (ZNRs) embedded with gold nanoparticles (Au NPs). A progressive increase in Au NP concentration introduces significant structural disorder and defects in ZNRs, which paradoxically quenches defect related visible PL while intensifying the near band edge (NBE) emission. Under UV excitation, the simulated semi-classical model realizes PL from ZnO with sub-bandgap defect states, eliciting visible emissions that are absorbed by Au NPs to generate a non-equilibrium hot carrier distribution. The photo-stimulated hot carriers, transferred to ZnO, substantially modify its steady-state luminescence, reducing NBE emission lifetime and altering the abundance of ionized defect states, finally reducing visible emission. The simulations show that the change in the interfacial band bending at the Au–ZnO interface under optical illumination facilitates charge transfer between the components. This work provides a general foundation to observe and model the hot carrier dynamics and strong light–matter interactions in hybrid plasmonic systems. [ABSTRACT FROM AUTHOR]

The temperature dependence of the optical properties of In0.4Ga0.6As0.98N0.02 quantum dots (QDs) was investigated using continuous-wave and time-resolved photoluminescence (PL). Significant increases in the PL peak energy and the PL linewidth were observed at temperatures above 200 K, which reflected the high luminescence efficiency of ground and excited states at high temperatures. The PL decay times of the ground state were almost constant between 200 and 300 K at 200–220 ps, which were significantly longer than that of 38 ps for the In0.4Ga0.6As QDs at 300 K. The temperature independence of the PL decay time represents significant suppression of the thermal escape and the thermal excitation of electrons because the electron ground-state localization energy is much larger than the thermal energy. The PL intensity of the In0.4Ga0.6As0.98N0.02 QDs was seven times stronger than that of the In0.4Ga0.6As QDs at 300 K, and this tendency was maintained up to 400 K with a PL intensity one order of magnitude stronger. These findings demonstrate that lowering the QD conduction band by nitrogen incorporation is an effective approach for achieving strong QD luminescence above room temperature. [ABSTRACT FROM AUTHOR]

Genes from ancient families are sometimes involved in the convergent evolutionary origins of similar traits, even across vast phylogenetic distances. Sulfotransferases are an ancient family of enzymes that transfer sulfate from a donor to a wide variety of substrates, including probable roles in some bioluminescence systems. Here, we demonstrate multiple sulfotransferases, highly expressed in light organs of the bioluminescent ostracod Vargula tsujii, transfer sulfate in vitro to the luciferin substrate, vargulin. We find luciferin sulfotransferases (LSTs) of ostracods are not orthologous to known LSTs of fireflies or sea pansies; animals with distinct and convergently evolved bioluminescence systems compared to ostracods. Therefore, distantly related sulfotransferases were independently recruited at least three times, leading to parallel evolution of luciferin metabolism in three highly diverged organisms. Reuse of homologous genes is surprising in these bioluminescence systems because the other components, including luciferins and luciferases, are completely distinct. Whether convergently evolved traits incorporate ancient genes with similar functions or instead use distinct, often newer, genes may be constrained by how many genetic solutions exist for a particular function. When fewer solutions exist, as in genetic sulfation of small molecules, evolution may be more constrained to use the same genes time and again.

The transition of energy from the 4f to the 5d state is a fundamental element driving various applications, such as phosphors and optoelectronic devices. The positioning of the 4f ground states and the 5d excited states significantly influences this energy shift. In our research, we delve into the placement of these states utilizing a hybrid density functional theory (DFT) combined with spin–orbit coupling (SOC) via the supercell method. Additionally, we scrutinize the transition energy, applying the constrained density functional theory (cDFT) approach in conjunction with the ΔSCF method. Our study illustrates that the synergy of cDFT and SOC generates a discrepancy of about 2% for Ce1 and 4% for Ce2 when comparing the calculated results to experimental data. Moreover, We have determined the positions of the 4f ground states to be 2.73 eV above the Valence Band Maximum (VBM) for Ce1 and 2.70 eV for Ce2. We also note a tight correlation between the 5d levels identified in the experimental data and the theoretical outcomes derived from wave function calculations at the CASPT2 accuracy level. [ABSTRACT FROM AUTHOR]

Ultrafast luminescence in Mg was investigated in the infrared region, between 0.35 and 1.05 eV, and compared with the results for Al, using a luminescence upconversion technique. The luminescence intensity of these metals at 0.9 eV was higher than that of platinum with a similar surface roughness under the same excitation density. Although the Mg and Al are adjacent to each other in the periodic table and belong to "light metals," having similar band structures, their luminescence spectra differ significantly. Pronounced peak structures were found for Mg and these were attributed to interband transitions within the conduction bands consisting of 3s and 3p orbitals overlapped on the intraband continuum, based on density functional theory band structure calculation. This result is in contrast to the interband luminescence in noble metals (Au, Ag, and Cu) under continuous-wave blue laser excitation, where the final states have been assigned to the d bands. A comparison of the spectra of rough and specular surfaces suggested that the surface roughness is not essential for mitigating wavenumber mismatch for intraband transitions. The luminescence from light metals, which are harmless to humans, will be attractive for biomedical applications. [ABSTRACT FROM AUTHOR]

The transition of energy from the 4f to the 5d state is a fundamental element driving various applications, such as phosphors and optoelectronic devices. The positioning of the 4f ground states and the 5d excited states significantly influences this energy shift. In our research, we delve into the placement of these states utilizing a hybrid density functional theory (DFT) combined with spin–orbit coupling (SOC) via the supercell method. Additionally, we scrutinize the transition energy, applying the constrained density functional theory (cDFT) approach in conjunction with the ΔSCF method. Our study illustrates that the synergy of cDFT and SOC generates a discrepancy of about 2% for Ce1 and 4% for Ce2 when comparing the calculated results to experimental data. Moreover, We have determined the positions of the 4f ground states to be 2.73 eV above the Valence Band Maximum (VBM) for Ce1 and 2.70 eV for Ce2. We also note a tight correlation between the 5d levels identified in the experimental data and the theoretical outcomes derived from wave function calculations at the CASPT2 accuracy level. [ABSTRACT FROM AUTHOR]

The luminescence properties of green Ba4Si6O16:Eu2+, rare-earths (RE) (RE = Sc, Y, La and Lu except Pm) phosphors are reported. Their long-lasting phosphorescence is discussed in view of trap depths and concentrations determined from thermally stimulated luminescence experiments. A second emission band centered at 439 nm was evidenced at low temperatures, which stems from the substitution of Eu2+ in the two non-equivalent Ba2+ sites of Ba4Si6O16. The mechanoluminescence properties of Ba4Si6O16:Eu2+, RE phosphors are described, and a new mechanoluminescence mechanism is proposed, in the case where RE = Ho3+, involving a trap distribution from 0.694 to 0.924 eV. Mechanical loading (post UV irradiation) induces a decrease in depth of the trap distribution, leading to an increase of the luminescence intensity, whereas a drop of the luminescence intensity is observed upon unloading, following the faster release of the charge carriers. [ABSTRACT FROM AUTHOR]

We discuss the possibility of using circularly polarized luminescence (CPL) as a tool to probe individual triplet spin sublevels that are populated nonadiabatically following photoexcitation. This study is motivated by a mechanism proposed for chirality-induced spin selectivity in which coupled electronic-nuclear dynamics may lead to a non-statistical population of the three triplet sublevels in chiral systems. We find that low-temperature CPL should aid in quantifying the exact spin state/s populated through coupled electronic-nuclear motion in chiral molecules. [ABSTRACT FROM AUTHOR]

Cd2+ cation doped CsPbCl3 single crystals were synthesized, and their luminescent properties were investigated under excitation with synchrotron radiation quanta with energy greater than Eg and at a sample temperature of 12 K. Pure single crystals exhibit a narrow band of exciton emission at 416.7 nm. Doping the single crystals leads to a high-energy shift of the excitonic luminescence, the appearance of new luminescent bands, the broadening of the luminescent bands, an increase in the decay time constants, and a significant enhancement of the luminescence intensity. The observed changes in luminescent parameters upon doping are discussed in terms of the crystal structure ordering, a decrease in the number of defects responsible for capturing charge carriers at the stage of electronic excitation thermalization, and a decrease in defects that quench excitonic luminescence. Doped single crystals with decay times of the order of 0.4 ns and intensities that significantly exceed the intensity of pure single crystals can be promising scintillation materials for positron emission tomography in the time-of-flight mode. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs), self-assembled by metal ions and organic ligands, have been utilized as active layers in resistive random-access memory (RRAM) devices due to their tunable composition and structure advantages, high porosity, and diverse interactions between guest molecules and host frameworks. As one kind of special MOF, MOF nanosheets not only inherit the benefits of MOFs but also present unique two-dimensional nanoscale thicknesses. Their special properties make them beneficial for fabricating MOF films. Thus, they could be promising materials for RRAM devices. Herein, we synthesized two porphyrin MOF nanosheets and then fabricated MOF films by spin-coating. After that, we used the films for resistive switching (RS) layers in memory devices. The as-fabricated RRAM devices exhibit write-once-read-many-times memory characteristics and good nonvolatile stability. Furthermore, due to the unique luminescence of the porphyrin linker, we investigated the light-induced resistive switching characteristics. The result shows that these porphyrin-based MOF nanosheet films exhibited ternary memory properties. This RS modulation is likely related to the photoinduced electrons and holes forming along channels consisting of porphyrin molecules. This MOF-based light-mediated memory device can be a candidate for achieving environment-responsive devices and has applications in information storage devices. [ABSTRACT FROM AUTHOR]

In this work, the absorption spectra of metastable Dy2+, Nd2+, and Sm2+  are identified in SrAl2O4:Eu,Ln persistent phosphors after excitation with blue light, thereby confirming that the persistent luminescence is indeed due to a charge transfer between the two lanthanide dopants. In contrast to previous studies relying on X‐ray absorption spectroscopy to observe charge transfers between dopants, here low‐energy light is exclusively employed to probe for changes in the absorption spectrum of the phosphor, thereby only minimally affecting the state of the phosphor. Optical bleaching in combination with thermoluminescence measurements allowed to assign which optically active trapping centers contribute to the afterglow of the persistent phosphors. [ABSTRACT FROM AUTHOR]

The structural, optical and temperature-dependent luminescence properties of Y2Mg2Al2Si2O12:Cr3+ phosphors were investigated for their multifunctional applications. The as-prepared phosphors exhibited an intense far-red emission band around 600-850 nm with a peak at 687 nm, which matches well with the absorption band of plant phytochromes. Importantly, the optimized sample showed excellent thermal stability and its emission intensity at 423 K maintained about 77% of that at 298 K. The potential application of the phosphors in plant-growth LED devices was also demonstrated. Furthermore, owing to the unique thermal quenching behavior of Cr3+, a three-mode luminescent thermometry system was designed based on fluorescent intensity (FL), fluorescent intensity ratio (FIR), and full width at half maximum (FWHM). The maximum temperature relative sensitivity (Sr) of each mode could reach 2.74% K-1, 1.09% K-1, and 1.47% K-1, respectively. These results indicate that the Y2Mg2Al2Si2O12:Cr3+ phosphors have potential applications for plant growth and optical thermometry. [ABSTRACT FROM AUTHOR]

Here, we report the formation of highly-stable and homogenous perovskite-based luminescent films with honeycomb-patterned surfaces by using the breath-figure method. The optimized PGPO@CsPbBr3 film exhibited uniform honeycomb-patterned pores that endowed it with uniform luminescence, high stability, and hydrophobicity. This work provides a new approach for fabricating highly-stable and homogenous perovskite-based luminescent films for full-color backlight displays. [ABSTRACT FROM AUTHOR]

Persistent phosphors possess unique afterglow optical properties. In this paper, a class of ultra-violet (UV) persistent luminescence nanoparticles were developed for catalytic photodegradation applications. UV persistent luminescence nanoparticles of SiO 2 -Zn 2 SiO 4 :Ga and SiO 2 -Zn 2 SiO 4 :Ga,Pb were successfully synthesized by using a mesoporous template method. The UV persistent luminescence intensity of SiO 2 -Zn 2 SiO 4 :Ga at 405 nm was enhanced up to ca. 3.5 times by co-doping with Pb2+ (396 nm), along with longer persistent luminescence duration. The photodegradation results indicate that it is useful to introduce UV persistent luminescence property into SiO 2 -Zn 2 SiO 4 :Ga,Pb to obtain enhanced catalytic activity of SiO 2 -Zn 2 SiO 4 with a bigger catalytic oxidation reaction kinetic constant (up to ∼4 times). This kind of UV persistent catalysis strategy may become a potential feasible method for better catalytic photodegradation activity. The UV persistent photocatalyst has potential applications in the photooxidation of organic molecules in high chroma and/or turbidity aqueous systems. [ABSTRACT FROM AUTHOR]

High transparency Ce3+-doped dense gadolinium aluminum borosilicate (GS x) glass scintillator was synthesized in reducing atmosphere by melt-quenching process. The transmittance of the glasses exceeds 80%, and the light attenuation length is between 5-20 cm within the range of 400–600 nm. GS x glass shows an photoluminescence (PL) in range of 350–550 nm, with the strongest emission peak around 420 nm. The PL decay time of GS x glasses is around 37 ns, with a maximum PL quantum yield of 44.05%. The integrated X-ray excited luminescence (XEL) intensity of GS S glass is 52.5% compared with BGO crystal. For X-ray imaging, GS L glass based imaging system shows a high spatial resolution of 9 lp/mm, which is comparable to CsI:Tl X-ray detectors. Under γ-ray, the highest light yield of GS S glass is 1235 ph/MeV with an energy resolution of 24.0% at 662 keV, close to that of BSO crystal. The scintillation decay time of GS x glasses is consisted of fast (∼100 ns) and slow (∼560 ns) components. In thermally stimulated luminescence (TSL), GS S glass exhibits a strong TSL peak at approximately 440 K, with low intensity shoulders at about 520 K, implying different types of defects and traps. Therefore, GS x glass has promising prospects for X-ray imaging and high-energy physics applications. [ABSTRACT FROM AUTHOR]

Series of gadolinium tantalum niobates activated with Eu3+ and Tb3+ ((Gd 1-y-z Eu y Tb z)Nb x Ta 1-x O 4 (x = 0, 0.3, 1; y = 0.6; z = 0.06; 0.15; 0.3)) were obtained for the first time. The formation of substitutional solid solutions was demonstrated. The obtained ceramic solid solutions had a monoclinic structure with I2/a space group. Electron probe microanalysis, photoluminescence (PL) and cathodoluminescence (CL) were used for studies of gadolinium tantalates and tantalum niobates series activated with Eu3++Tb3+. CL and PL spectra, concentration dependences of CL intensity and decay times, as well as excitation spectra for 5D 0 -7F 2 Eu3+ and 5D 4 -7F 5 Tb3+ bands were analyzed. It was shown for the first time that both energy transfer from Tb3+ to Eu3+ ions, and a reverse process – energy transfer from Eu3+ to Tb3+ ions are observed. This reverse process led to a decrease in CL intensity and decay times of europium bands in the presence of terbium 3+ in these materials. Presumably this phenomenon is influenced by anti-Stokes luminescence. This is confirmed by the dependences of anti-Stokes luminescence probability on temperature and excitation density. [ABSTRACT FROM AUTHOR]

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 La 3 Sc 2 Ga 3 O 12 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. [ABSTRACT FROM AUTHOR]

The orange-red phosphor, which combines persistent luminescence and mechanoluminescence, holds significant importance in advanced bioimaging and optical anti-counterfeiting. However, there are relatively few reports on this type of material currently. In this study, doping CaAl 2 Si 2 O 8 : Mn2+ phosphor with Pr3+ ions significantly increases the material's defect density. Under X-ray/UV excitation, the sample displays exceptional orange-red persistent luminescence and superior mechanoluminescence. More importantly, the samples exhibit the above properties in all temperature regions (including low temperature, room temperature (RT) and high temperature). Additionally, the material demonstrates excellent tissue penetration capabilities and dual-mode luminescence (persistent luminescence and mechanoluminescence), highlighting its potential for bioimaging and optical anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]

Oxyapatites A10(GeO4)6O2 (A – alkaline, rare‐earth elements) are considered promising materials for applications in solid‐state lighting and non‐contact thermometry. The temperature dynamics of the oxygen sublattice have a crucial influence on the luminescent properties of these optical hosts. Here, the structural evolution with temperature of germanates with the general formula ALa9(GeO4)6O2 (A – Li, Na, K, Rb) is investigated, using X‐ray and neutron powder diffraction methods. These compounds crystallize in space‐group P63/m. NPD experiments helped to determine the oxygen and alkaline metal positions. Thermally‐induced reentrant structural transitions relating to the oxygen in the apatite channel are discovered for the first time. In the example of Eu‐doped RbLa9(GeO4)6O2 and KLa9(GeO4)6O2, it is demonstrated that the luminescence of the Eu3+ ion is influenced by small changes in the crystal structure. [ABSTRACT FROM AUTHOR]

Reducing the driving voltage is a long‐term and important challenge in the development of light‐emitting diodes (LEDs) because the light‐emission threshold voltage cannot be below the theoretical limit of the emitter's bandgap divided by the elementary charge. Here, green perovskite nanocrystal (PeNC) LEDs are inverted that emit light at ultralow voltages (below the theoretical limit) realized by efficient Auger‐assisted energy up‐conversion at the interface of the zinc oxide nanoparticles (ZnO NPs) electron injection layer and PeNC light‐emission layers. The up‐conversion utilizes the recombination energy of the charge‐transfer excitons. After modifying the interface by plasma treatment of the ZnO NPs and by inserting an organic interlayer between the ZnO NPs and PeNCs, the device performance is dramatically improved from that of the unmodified PeNC LED. The threshold voltage at which the emission spectrum can be observed is 1.55 V, substantially lower than 2.34 V (the PeNC emitter's bandgap divided by the elementary charge). Moreover, after mixing an organic aromatic semiconductor compound in the PeNC light‐emission layer, the carrier balance is regulated and the threshold voltage is further reduced to 1.30 V. [ABSTRACT FROM AUTHOR]

Luminescent materials that respond to changes in microscopic chemical conditions are essential for visualizing and evaluating molecular environments. Boron complexes are often employed as robust scaffolds for constructing such responsive systems because of their inherent stimuli‐responsive properties. However, in the case of nonresponsive luminophores, the absence of these intrinsic features limits their range of applications. In this study, environment‐responsive luminescent homopolymers based on the boron β‐dialdiminate complex are developed, which is intrinsically less responsive, by introducing optimized side chains. As a key finding, the triethylene glycol‐decorated polymer exhibits more intense luminescence in chloroform but weaker luminescence in N,N‐dimethylformamide. Structural analyses using NMR and size‐exclusion chromatography suggest that this polymer forms larger aggregates in polar solvents because of the solvophobicity of its main chain, while the polar side chains assist in maintaining adequate dispersibility of these aggregates. Photophysical measurements indicate that interchromophore interactions within the aggregates should be responsible for the reduced luminescence in polar solvents. These findings suggest that side‐chain engineering should be an effective strategy for creating stimuli‐responsive polymers from otherwise nonresponsive luminophores. [ABSTRACT FROM AUTHOR]

Photo-stimulated luminescent materials are one of the most attractive alternatives for next-generation optical information storage technologies. However, there are still some challenges in regulating appropriate energy levels of traps in luminescent materials for optical information storage. Herein, a green emission nanophosphor Zn 2 SiO 4 : Mn2+, Cr3+ with the trap depth of 1.05 eV, fulfilling the requirements for optical information storage, was fabricated for the first time through the solution combustion method and subsequent heat treatment at 1000 °C for 2 h. The crystal structure, micromorphology, photoluminescence (PL), photoluminescence excitation (PLE), and afterglow properties of Zn 2 SiO 4 : Mn2+, Cr3+ were studied systematically. By applying the strategy of trap depth engineering, high trap density with proper trap depth was observed when Cr3+ ions were introduced into Zn 2 SiO 4 : Mn2+. Thermoluminescence (TL) glow-curve analysis through the initial rise (IR) method was conducted to gain some insights into the information of traps. As proof of application, optical information storage was experimentally achieved by choosing 275 nm illumination for "information writing" and 980 nm NIR excitation for "information reading". The results indicate that Zn 2 SiO 4 : Mn2+, Cr3+ phosphor holds promise for potential applications in the field of optical information storage. [ABSTRACT FROM AUTHOR]

Two new structural motifs within the class of heteroleptic PdnAnBn assemblies, namely syn‐cis‐Pd3A3B3 bowls and bowl‐ (syn) or saddle‐ (anti) shaped cis‐Pd4A4B4 rings are introduced. All of the ten examples share a common longer fluorenone‐based bis‐monodentate ligand, equipped with meta‐pyridine donor groups. The ring size (3‐ vs. 4‐membered) and conformational preference (bowl vs. saddle) are controlled by the choice of the shorter ligand. These carry para‐pyridine donors, different aromatic backbones (benzene, thiophene or selenophene) and either no or small or bulky endohedral substituents, serving to control the nuclearity of the heteroleptic rings through different effects (ligand angle, charge distribution or backbone bulk). Moreover, the luminescence of the fluorenone ligand is conserved in the formed architectures. Emission intensity as well as host–guest properties vary depending on the inward‐pointing functions. All Pd3A3B3 assemblies are shown to bind chiral guest BINOL bis‐sulfonate which imparts its chirality to the entire host–guest complex. This results in a guest‐induced circular dichroism (CD) and circularly polarized luminescence (CPL) with dissymmetry factor glum up to 10−3. [ABSTRACT FROM AUTHOR]

Lanthanide‐based upconversion molecular complexes have potential application in diverse fields and attracted considerable research interest in recent years. However, the similar coordination reactivity of lanthanide ions has constrained the designability of target molecule with well‐defined structure, and many attempts obtained statistical mixtures. Herein, an ion‐paired Yb−Eu heteronuclear complex [Eu(TpPy)2][Yb(ND)4] (TpPy=tris[3‐(2‐pyridyl)pyrazolyl]hydroborate, ND=3‐cyano‐2‐methyl‐1,5‐naphthyridin‐4‐olate) was designed and synthesized. Thanks to the radius difference between Eu3+ (1.07 Å) and Yb3+ (0.98 Å) ions, the hexadentate TpPy ligand was selected to coordinate with Eu3+ and the Yb3+ with a smaller radius was chelated by bidentate ND ligand. As a result, the sites of Eu3+ and Yb3+ in the complex can be clarified by high‐resolution mass spectrometry and single‐crystal structure analysis. Upon the excitation of Yb3+ at 980 nm, the upconversion emission of Eu3+ was realized through a cooperative sensitization process. Furthermore, [Eu(TpPy)2][Yb(ND)4] demonstrated excellent photostability during continuous high‐power density 980 nm laser irradiation, with a LT95 (the time to 95 % of the initial emission intensity) of 420 minutes. This work provides the first example of a pure ion‐paired Yb−Eu heteronuclear complex upconversion system and may bring insights into rational design of lanthanide‐based upconversion molecular complexes. [ABSTRACT FROM AUTHOR]

Thorium, a predominant actinide in the Earth's crust, presents significant environmental and health risks due to its radioactive nature. These risks are particularly pronounced during the mining and processing of monazite for rare earth elements (REEs), which contain substantial thorium concentrations. Current instrumental analysis methods for thorium, offer high accuracy but require laborious sample preparations and expensive instruments, making them unsuitable for on‐site analysis. Herein, we present a class of color‐tunable luminescent lanthanide‐based metal–organic frameworks (Ln‐MOFs) as fluorochromic sensors for Th4+ cations. Utilizing a heterobimetallic Eu3+/Tb3+ doping strategy, the luminescence colors of EuxTb1‐x‐BDC‐OH can be finely tuned from red, to orange, and to green. More intriguingly, the higher Lewis acidity of Th4+ facilitates the transformation of EuxTb1‐x‐BDC‐OH into a UiO‐type Th‐MOF via a dissolution‐recrystallization mechanism. This process results in a gradual reduction of characteristic Ln3+ emissions and the emergence of blue color ligand‐based fluorescence, thereby leading to selective fluorochromic responses with increasing Th4+ concentrations and enabling visible detection of Th4+ cations. Additionally, a custom‐built portable optoelectronic device is fabricated, which directly converts luminescence colors into red‐green‐blue (RGB) values. This device enables easy quantification of Th4+ concentrations without the need for complex instrumentation. [ABSTRACT FROM AUTHOR]

Copper indium selenide (CISe) is a prototype infrared semiconductor with low toxicity and unique optical characteristics. Its quantum dots (QDs) accommodate ample intrinsic point defects which may actively participate in their rather complex photophysical processes. We synthesize CISe QDs with similar sizes but with distinct highly stoichiometry-deviating atomic ratios. The synthesis condition employing Se-rich precursors yields the Cu-deficient CISe QDs with special photophysical properties. The photoluminescence exhibits monotonic red shift from 680 to 775 nm when the ratio of Cu's proportion to In's decreases. The luminescence is found to stem from the copper vacancy and antisite defects. The CISe QDs exhibit Raman activity at 5.6, 6.9, and 8.7 THz that is separately assigned to Cu–Se and In–Se optical phonon modes and surface mode. [ABSTRACT FROM AUTHOR]

The past decades have witnessed the significant development and practical interest of in vivo biomedical imaging technologies and optical materials in the second‐near infrared (NIR‐II, 1000–1700 nm) window. Imaging with the extended emission wavelength toward the long‐wavelength end (NIR‐IIb, 1500–1700 nm) further offers micrometer imaging resolution and centimeter tissue penetration depth by taking advantage of the much‐reduced photon scattering and near‐zero tissue autofluorescence background, which have become a very hot research area. This review focuses on the recent advances in the development of lanthanide‐based NIR‐IIb probes for in vivo biomedical applications. The progress including ratiometric imaging, multiplexed imaging for wide‐field and microscopy, lifetime multiplexing and sensing, persistent luminescence, and multimodal imaging is summarized. Challenges and future directions concerning the investigation of the photophysical and photochemical properties of NIR‐IIb probes, the selection of near‐infrared cameras as well as the potential extension of the NIR‐IIb imaging sub‐window are pointed out. This review will inspire readers who have a strong interest in developing optical imaging technology and long‐wavelength fluorescence probes for high‐contrast in vivo biomedical applications. [ABSTRACT FROM AUTHOR]

Development of ultra‐broadband visible‐to‐near‐infrared (VIS‐NIR) luminescent materials is a challenging but rewarding endeavor, as they are highly desirable for a number of applications in photonics, optoelectronics, and biological sciences. Nevertheless, to date, rare earth‐doped phosphors that can be efficiently excited by blue light and produce broadband emission in the VIS‐NIR regions remain scarce. In this study, a series of Ce3+‐doped Ba3M4O9 (M = Sc, Lu, Y) broadband luminescent materials are designed based on low‐coordination crystallographic lattice engineering. Among these materials, Ba3Y4O9:Ce3+ produces a continuous ultra‐wide VIS‐NIR emission (λem = 660 nm) in the range of 500–950 nm under 410 nm light excitation. This emission wavelength is the longest among those observed in Ce3⁺‐doped oxide materials. Structural refinement, theoretical calculation, and spectral analysis demonstrate that this VIS‐NIR broadband emission is attributed to the occupying multiple distorted octahedral lattice sites by Ce3+ in Ba3Y4O9. Several strategies are employed to enhance the luminescence intensity and thermal stability of this material, including the use of carbon paper coating, the incorporation of co‐solvents, and the addition of GeO₂ or ZrO₂. Furthermore, the as‐prepared materials demonstrate multifunctional applications in white light‐emitting diodes (WLED), night vision, and fluorescent thermometers. This study offers insights into the design of Ce3+‐doped ultra‐wide VIS‐NIR light‐emitting materials. [ABSTRACT FROM AUTHOR]

Scintillators, essential for applications in nuclear medicine, radiation detection, and industrial inspection, convert high‐energy radiation into visible light. Manganese (Mn)‐based inorganic–organic hybrid materials are distinguished by their thermal stability, mechanical strength, and flexibility. However, the effects of temperature on Mn(II)‐based hybrid scintillators have not been clearly analyzed, making the elucidation of their temperature‐dependent luminescence mechanisms particularly important. A notable advancement is the synthesis of Mn‐1 nanocrystals (NCs) using methyltriphenylphosphonium chloride (mtppCl) and MnCl₂. These NCs exhibit distinctive temperature‐dependent photoluminescence luminescence: the intensity decreases from 77 to 150 K but paradoxically increases at higher temperatures due to anomalous thermal exciton behavior in the [MnCl₄]2⁻ tetrahedra. Besides, Mn‐1 NCs achieve a detection limit of 1.01 µGyair/s, surpassing medical diagnostic standards and outperforming commercial scintillators such as Bi₄Ge₃O₁₂ (BGO). Additionally, they show exceptional stability under continuous irradiation and can be incorporated into a flexible scintillating film with a resolution of 11.3 lp/mm at an MTF of 0.2. The current study has further refined the luminescence mechanism of Mn(II)‐based materials and optimizes their properties for a wider range of applications. [ABSTRACT FROM AUTHOR]

Accurate quantification of efficiency enables rigorous comparison between different photoluminescent materials, providing an optimization path critical to the development of next‐generation light sources. Persistent luminescent materials exhibit delayed and long‐lasting luminescence due to the temporary storage of optical energy in engineered structural defects. Standard characterization methods do not provide a universal comparison of phosphor performance, hindering the evaluation of the efficiency of the various processes involved in afterglow. Here, a protocol is established to determine the quantum yield of persistent phosphors by considering the ratio of photons emitted in the afterglow and during charging to those absorbed. The method is first applied to transparent single crystals of the most common persistent phosphors, such as SrAl2O4:Eu2+,Dy3+ and Y3Al2Ga3O12:Ce3+,Cr3+. The versatility of the methodology is demonstrated by quantifying the quantum yield of a ZnGa2O4:Cr3+ thin film, a material widely used in in vivo imaging. The high efficiency of strontium aluminate is confirmed, and a strong dependence of the obtained values on the illumination conditions is revealed, highlighting a trade‐off between efficiency and brightness. The results contribute to the development of standardized protocols for analyzing afterglow mechanisms and assessing overall efficiency, facilitating rigorous comparison and optimization of persistent materials beyond trial‐and‐error approaches. [ABSTRACT FROM AUTHOR]

The microwave‐assisted methodology is now extended and fine‐tuned for the synthesis of mixed‐ligand europium complexes with an average reaction time of 12 min. Overall, 14 different complexes were synthesized to improve luminescence using our previously proposed strategy to boost luminescence through ligand diversification, specifically by applying it to quaternary europium complexes with at least one DBM (1,3‐diphenylpropane‐1,3‐dionate) ligand. DBM is a strong absorbant of UV radiation that can dissipate energy through nonradiative channels; thus, it is a useful molecular scaffold for sunblockers and cosmetics. Accordingly, the following luminescent tetrakis and quaternary complexes were prepared: K[Eu(DBM)4], K[Eu(β)4], K[Eu(DBM)3(β)], K[Eu(DBM)2(β)2], K[Eu(DBM)2(β)(β’)], and the fully mixed complex K[Eu(DBM)(BTFA)(TTA)(HFAC)], where β can be either BTFA (4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate), TTA (4,4,4‐trifluoro‐1‐(2‐thienyl)butane‐1,3‐dionate), or HFAC (1,1,1,5,5,5‐hexafluoropentane‐2,4‐dionate). For all the complexes, luminescence experiments were performed in chloroform and acetone solutions. Our findings confirm that mixed‐ligand complexes exhibit superior quantum efficiencies compared to the average of their homoleptic counterparts. The presence of DBM in the complexes tends to dramatically increase the nonradiative decay rates of the solutions. Finally, we present formulae that provide a detailed understanding of the distinctive roles of each ligand and their relevant interactions in luminescence. [ABSTRACT FROM AUTHOR]

White afterglow is very appealing both in scenario‐specific luminescence and background‐free bio‐imaging, while it is challenging to obtain stable white afterglow due to the difficulty in matching the emission lifetimes of complementary colors. It is reported here that assisted partial phosphorescence resonance energy transfer (ap‐PRET) can be a very efficient way toward this goal. When a blue afterglow of energy donor with long lifetime is obtained in a polymeric network displaying phosphorescent clusterization‐triggered emission (CTE), the network assisted partial phosphorescence resonance energy transfer (ap‐PRET) between it and a yellow fluorescent acceptor would yields orange afterglow. Owing to the energy supply of the CTE network, the lifetime of the donors blue afterglow can be tuned close to that of the acceptors orange afterglow through ap‐PRET in a wide donor to accepter ratios, and emissions ranging from the cold to warm white afterglows can be obtained. Amazingly, these white afterglows are along the blackbody radiation line in the CIE plot, disclosing the powerful ability of ap‐PRET in generating desired white afterglows for applications in diversified luminescent scenarios. [ABSTRACT FROM AUTHOR]

Viologen-based photochromic materials with photochromicity and photoluminescence have great advantages in anti-counterfeiting applications. Two novel viologen-based multifunctional Ln-MOFs Eu2Cl(m-bpybdc)L2(NO3)2·(H2O)5 (1) and Tb2Cl(m-bpybdc)L2(NO3)2·(H2O)6 (2) (m-bpybdc = 1,1′-bis(3-carboxyphenyl)-4,4′-bipyridinium and H2L = isophthalic acid) with three-dimensional structures were synthesized solvothermally. Both compounds exhibited reversible discoloration in response to external light and electrical stimulation. Notably, compound 1 presented strong fluorescence under ultraviolet light, showing the characteristic red emission of Eu3+. We further explored the application of these compounds in the field of anti-counterfeiting. These results provide useful data on the structure, luminescence, and light response of viologen-based lanthanide coordination polymers for their effective application. [ABSTRACT FROM AUTHOR]

Utilizing the flexible carboxylic acid ligand, tri (4‐carboxybenzyl) amine (H3L), three new metal organic frameworks Na[Cd(L)]n ⋅ 3nH2O (1), [Cd(HL)(4,4'‐bipy)0.5(H2O)]n (2) (4,4'‐bipy=4,4'‐bipyridine) and [Cd(HL)(2,2'‐bipy)]n (3) (2,2'‐bipy=2,2'‐bipyridine) have been successfully synthesized. Compounds 1 and 2 are 2D structures with (3,6) 2‐nodal as kgd topology, while compound 3 is a 1D chain structure. The powder X‐ray diffraction and thermal stability of 1–3 were studied. In addition, the solid‐state luminescence properties of compounds 1–3 at room temperature were also tested, indicating their application prospects in fluorescent materials. [ABSTRACT FROM AUTHOR]

The fight against counterfeiting is a crucial concern for economies around the world, underscoring the urgent need for effective measures to ensure the legitimacy of products and documents. Luminescent security inks have emerged as effective tools in this battle. The third generation of these inks, incorporating stimuli‐responsive organic materials, enables unique efficiency. In this work, the stimuli‐responsive behavior of three trialkylated triazatruxene dimers (TRI1, TRI2, and TRI3), endowed with N‐alkyl chains of different length is investigated. Among them, TRI3, with three flexible dodecyl chains, shows remarkable stimuli‐responsive fluorescence that is attributed to thermally or shear‐induced phase transitions between a tetragonal columnar phase and a discotic‐nematic liquid crystal phase. Such transformation involves the breakdown of highly emissive J‐aggregates with a strong influence on the resulting emissive color. Interestingly, these stimuli‐triggered transformations are spontaneously reversed, which renders this compound very interesting in the search of third‐generation security inks. [ABSTRACT FROM AUTHOR]

The realization of persistent luminescence and in particular circularly polarized luminescence (CPL) of organic radicals remains a challenge due to their sensitivity to oxygen at ambient conditions and elusive excited state chirality control. Here, it is reported that UV‐irradiation on a supramolecular gel from a chiral triarylamine derivative, TPA‐Ala, led to the formation of luminescent radicals with bright CPL. TPA‐Ala can form an organogel in chloroform with blue emission and supramolecular chirality as demonstrated by both CD and CPL signals. Upon UV 365 nm irradiation, an emission color change from blue to cyan is observed due to the formation of photo‐induced radicals. Interestingly, it is found that the supramolecular gel radicals showed stable luminescence with a lifetime ≈ 10 days in dark environments and inverted CPL, which represents a scarce example with persistent CPL from doublet‐state due to oxygen isolation ability of the gel network. Furthermore, doping a guest dye, Rhodamine B (RhB), into the supramolecular gel (RhB/TPA‐Ala = 30% in molar ratio) successfully obtained a transient white‐light CPL through the superposition of photo‐induced radical and guest dye emissions. This work provides a useful methodology for the fabrication of radical‐based CPL materials via a supramolecular assembly approach. [ABSTRACT FROM AUTHOR]

Upconverting particles (UCPs), renowned for their capability to convert infrared to visible light, serve as invaluable imaging probes. Furthermore, their responsiveness to diverse external stimuli holds promise for leveraging UCPs as remote multiparametric sensors, capable of characterizing medium properties in a single assessment. However, the utility of UCPs in multiparametric sensing is impeded by crosstalk, wherein distinct external stimuli induce identical alterations in UCP luminescence, hindering accurate interpretation, and yielding erroneous outputs. Overcoming crosstalk requires alternative strategies in upconverting luminescence analysis. In this study, it is shown how a single spinning NaYF4:Er3+, Yb3+ upconverting particle enables simultaneous and independent readings of temperature and viscosity. This is achieved by decoupling thermal and rehological measurements—employing the luminescence of thermally‐coupled energy levels of Er3+ ions for thermal sensing, while leveraging the polarization of luminescence from non‐thermally coupled levels of Er3+ ions to determine viscosity. Through simple proof‐of‐concept experiments, the study validates the capability of a single spinning UCP to perform unbiased, simultaneous temperature, and viscosity sensing, thereby opening new avenues for advanced sensing in microenvironments. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (quasi‐2D) perovskites, consisting of multi‐quantum wells (MQWs) separated by organic intercalating cations, exhibit high luminescence efficiency while the photophysical processes involved remain partially obscure due to the uncertainty of the MQWs structure. Herein, a synergetic dual‐additive strategy is adopted to prepare quasi‐2D perovskite films, where 18‐crown‐6 and tris(4‐fluorophenyl)phosphine oxide are utilized to suppress the formation of low‐dimensional perovskites, diminish defect density, and enhance photoluminescence quantum yield to 93.7%. Notably, a long‐lived delayed component, spanning hundreds of microseconds, is identified for the first time in perovskite emitters, which correlates with exciton dissociation and recombination, and the differences in temperature‐dependent radiative lifetime of the delayed components match with the luminescence properties. Finally, benefiting from lower trap density and more efficient energy‐funneling, green PeLEDs treated with dual additives have achieved a high external quantum efficiency of 28.9% and a commendable operating half‐lifetime of 17.8 h at an initial brightness of 500 cd m−2. The observation of the long‐lived delayed components, coupled with insights into exciton dissociation, provides a profound and comprehensive understanding of the fundamental carrier behavior in perovskite emitters and establishes a direct correlation between the properties of perovskite emitters and their photophysical processes. [ABSTRACT FROM AUTHOR]

Lead‐free halide double perovskites (DPs) have attracted much attention due to their potential applications in the field of near‐infrared (NIR) optoelectronics. However, regulating the NIR luminescence properties of such materials remains a challenge. In this study, it is found that Cs2AgInCl6:Cr3+ DPs exhibit a broad NIR emission under ultraviolet excitation, with a peak value of 980 nm. In the range of 9 GPa, the emission intensity increases significantly. As the pressure increases, a transition from broadband NIR emission to narrow‐line emission occurs, accompanied by a decrease in the full width at half maximum (FWHM) from 260 to 40 nm, attributed to increased local structural asymmetry and enhanced crystal field around Cr3+ ions. Ultrafast transient absorption experiments reveal the changes of energy transfer under pressure and the emergence of new radiation channels, demonstrating the dynamic evolution of emission characteristics under high pressure. The research results deepen the understanding of high pressure luminescence in Cr3⁺‐doped halide DPs, providing strategies for designing highly efficient NIR emitters in metal halide DPs. [ABSTRACT FROM AUTHOR]

Lead‐free halide perovskites (LHP) have attracted extensive attention in the field of next‐generation solid‐state lighting. However, single perovskite phosphor with tunable white‐light emission and ultra‐high photoluminescence quantum yield (PLQY) are rare. Here, the tunable dual‐color emission LHP phosphor is developed with a near‐unity PLQY of 99.5%. The LHP phosphor comprises Cs2NaInCl6: Sb3+/Bi3+ and Cs2InCl5·H2O: Sb3+/Bi3+ crystals, with the transition between these two perovskite structures being adjustable by the concentration of Na+. The addition of NaCl inhibits the hydrolysis of the [Sb(H2O)Cl5]2− octahedron, resulting in 3D connected [SbCl6]3− octahedron with less Jahn‐Teller distortion, and the PLQY of LHP is greater than 90%. Finally, the white‐light diode device is fabricated by assembling the LHP with a ultraviolet light‐emitting diode  chip and the white light‐emitting diode device achieved Commission Internationale de l'Eclairage color coordinates of (0.34, 0.33), correlated color temperature of 4936 K, and a high color rendering index of 92.9. The LHP perovskite exhibited multimodal luminescence when excited by 365, 335, and 310 nm UV light, showing the multi‐mode anti‐counterfeiting capabilities of the LHP crystals. [ABSTRACT FROM AUTHOR]

Acenes are attractive as building blocks for low gap organic materials with applications, for example, in organic light emitting diodes, solar cells, bioimaging and diagnostics. Previously, we have shown that modification of dipyridylanthracene via B–N Lewis pair fusion (BDPA) strongly redshifts the emission, while facilitating self‐sensitized reactivity toward O2 to reversibly generate the corresponding endoperoxides. Herein, we report on the further expansion of the π‐system of BDPA to a vinyl‐substituted monomer, vinylene‐bridged dimer, and a polymer with an average of 20 chromophores. The extension of π‐conjugation results in largely reduced band gaps of 1.8 eV for the dimer and 1.7 eV for the polymer, the latter giving rise to NIR emission with a maximum at 731 nm and an appreciable quantum yield of 7 %. Electrochemical and computational studies reveal efficient delocalization of the lowest unoccupied molecular orbital (LUMO) along the pyridyl‐anthracene‐pyridyl axis, which results in effective electronic communication between BDPA units, selectively lowers the LUMO, and ultimately narrows the band gap. Time‐resolved emission and transient absorption (TA) measurements offer insights into the pertinent photophysical processes. Extension of π‐conjugation also slows down the self‐sensitized formation of endoperoxides, while significantly accelerating the thermal release of singlet oxygen to regenerate the parent acenes. [ABSTRACT FROM AUTHOR]