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Pr 2 NiO (4+δ) coatings of rare earth nickelate oxide were prepared through RF magnetron co-sputtering, combined with an appropriate heat treatment. The study focused on optimizing the growth conditions to enhance the thermal emittance of the coatings, taking into account the influence of thickness and roughness. The research findings revealed interesting insights. Firstly, by analyzing room temperature infrared reflectivity and studying the temperature dependence of the normal spectral emittance in the range of 500 cm −1 to 5500 cm −1 , it was observed that the total emittance increased as the coating thickness increased. However, this increase tended to approach a saturation value at higher thicknesses. Additionally, the study demonstrated that a coating thickness of 2.8 μm was sufficient to effectively shield the substrate's infrared thermal response. This suggests the potential application of these coatings for thermal management purposes. Furthermore, the influence of roughness on the emittance was predominantly observed in the spectral range of 1200 cm −1 to 3600 cm −1 . This finding highlights the importance of considering surface roughness when designing coatings for optimal thermal properties. In summary, the research provided valuable insights into the growth conditions and the impact of thickness and roughness on the thermal emittance of Pr 2 NiO 4+δ coatings. These findings contribute to the development of improved materials for thermal management and related applications.

We study the relation between angular spectral absorptivity and emissivity for any thermal emitter, which consists of any linear media that can be dispersive, inhomogeneous, bianisotropic, or nonreciprocal. First, we establish an adjoint Kirchhoff’s law for mutually adjoint emitters. This law is based on generalized reciprocity and is a natural generalization of conventional Kirchhoff’s law for reciprocal emitters. Using this law, we derive all the relations between absorptivity and emissivity for an arbitrary thermal emitter We reveal that such relations are determined by the symmetries of the system, which are characterized by a Shubnikov point group. We classify all thermal emitters based on their symmetries using the known list of all three-dimensional Shubnikov point groups. Each class possesses its own set of laws that relates the absorptivity and emissivity. We numerically verify our theory for all three types of Shubnikov point groups: Gray groups, colorless groups, and black and white groups. We also verify the theory for both planar and nonplanar structures with single or multiple diffraction channels. Our theory provides a theoretical foundation for further exploration of thermal radiation in general media.

Perovskite light-emitting diodes (LEDs) show promises for next-generation displays owing to their excellent luminescent properties and low cost. Despite substantial progress with green- and red-emitting devices, the development of efficient blue perovskite LEDs has lagged behind. Here we demonstrate efficient blue perovskite LEDs based on a mixed two-dimensional–three-dimensional perovskite and a multifunctional ionic additive that enables control over the reduced-dimensional phases, non-radiative recombination channels and spectral stability. We report a series of devices that emit efficient electroluminescence from mixed bromide/chloride quasi-three-dimensional regions, with external quantum efficiencies of up to 21.4% (at a luminance of 22 cd m –2 and emission peak at 483 nm), 13.2% (at a luminance of 2.0 cd m – 2 and emission peak at 474 nm) and 7.3% (at a luminance of 6 cd m –2 and emission peak at 464 nm). Devices show a nearly 30-fold increase in operational stability compared with control LEDs, with a half-lifetime of 129 min at an initial luminance of 100 cd m –2 . Our findings demonstrate the performance of blue perovskite LEDs close to that of state-of-the-art blue organic LEDs and inorganic quantum dot LEDs and provide a new approach to design multifunctional molecules to boost the performance of perovskite optoelectronic devices. Addition of a multifunctional ionic additive in mixed two-dimensional–three-dimensional bromide/chloride perovskites enables efficient blue perovskite LEDs with external quantum efficiency of up to 21.4% and half-lifetime of 129 min at an initial luminance of 100 cd m –2 .

The transition from 3rd to 4th generation synchrotron light sources via Diffraction Limited Storage Rings (DLSRs) is largely de=ined by the reduction of horizontal emittances and, in turn, achieving more uniform transverse X-ray beam pro=iles. Previously at Advanced Photon Source (APS), SPECTRA simulations were performed to compare to the vertical emittance measurements made at the IEX undulator and beamline. The alignment in measurement and simulation drove the desire to measure the horizontal emittance at the APS-Upgrade. Simulations in SPECTRA and ongoing work in Synchrotron Radiation Workshop (SRW) guide our experimental strategy. In the present work, results from SRW will be presented. We will then conclude with commissioning measurements of beam size and emittance in the APS-U as well as a discussion on the advantages to the undulator high harmonics method when compared to other methods at the APS-U.

By alloying GaN with AlN the emission of AlGaN light-emitting diodes can be tuned to cover almost the entire ultraviolet spectral range (210–400 nm), making ultraviolet light-emitting diodes perfectly suited to applications across a wide number of fields, whether biological, environmental, industrial or medical. However, technical developments notwithstanding, deep-ultraviolet light-emitting diodes still exhibit relatively low external quantum efficiencies because of properties intrinsic to aluminium-rich group III nitride materials. Here, we review recent progress in the development of AlGaN-based deep-ultraviolet light-emitting devices. We also describe the key obstacles to enhancing their efficiency and how to improve their performance in terms of defect density, carrier-injection efficiency, light extraction efficiency and heat dissipation.This Review covers recent progress in AlGaN-based deep-ultraviolet light-emitting devices. The key technologies of how to improve their performance, carrier-injection efficiency, light extraction efficiency and heat dissipation are discussed.

The full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of \\[^{100}\\]Mo to the ground state of \\[^{100}\\]Ru, \\[T_{1/2} = \\left[ 6.81 \\pm 0.01\\,\\left( \\text{ stat }\\right) ^{+0.38}_{-0.40}\\,\\left( \\text{ syst }\\right) \\right] \\times 10^{18}\\] year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of \\[5\\times 10^5\\] events and a signal-to-background ratio of \\[\\sim \\] 80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of \\[\\mathrm{n}=2,3,7\\], as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained.

Chemically made colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. We now demonstrate that individual colloidal lead halide perovskite quantum dots (PQDs) display highly efficient single-photon emission with optical coherence times as long as 80 picoseconds, an appreciable fraction of their 210-picosecond radiative lifetimes. These measurements suggest that PQDs should be explored as building blocks in sources of indistinguishable single photons and entangled photon pairs. Our results present a starting point for the rational design of lead halide perovskite–based quantum emitters that have fast emission, wide spectral tunability, and scalable production and that benefit from the hybrid integration with nanophotonic components that has been demonstrated for colloidal materials.

Pure organic room temperature phosphorescence (RTP) materials become increasingly important in advanced optoelectronic and bioelectronic applications. Current phosphors based on small aromatic molecules show emission characteristics generally limited to short wavelengths. It remains an enormous challenge to achieve red and near-infrared (NIR) RTP, particularly for those from nonaromatics. Here we demonstrate that succinimide derived cyclic imides can emit RTP in the red (665, 690 nm) and NIR (745 nm) spectral range with high efficiencies of up to 9.2%. Despite their rather limited molecular conjugations, their unique emission stems from the presence of the imide unit and heavy atoms, effective molecular clustering, and the electron delocalization of halogens. We further demonstrate that the presence of heavy atoms like halogen or chalcogen atoms in these systems is important to facilitate intersystem crossing as well as to extend through-space conjugation and to enable rigidified conformations. This universal strategy paves the way to the design of nonconventional luminophores with long wavelength emission and for emerging applications. Pure organic room temperature phosphorescence (RTP) materials become increasingly important but achieving red and near-infrared (NIR) RTP remains challenging. Here, the authors demonstrate that succinimide derived cyclic imides can emit RTP in the red and NIR spectral range with outstanding efficiencies of up to 9.2%.

Perovskite light-emitting diodes (PeLEDs) have showed significant progress in recent years; the external quantum efficiency (EQE) of electroluminescence in green and red regions has exceeded 20%, but the efficiency in blue lags far behind. Here, a large cation CH 3 CH 2 NH 2 + is added in PEA 2 (CsPbBr 3 ) 2 PbBr 4 perovskite to decrease the Pb–Br orbit coupling and increase the bandgap for blue emission. X-ray diffraction and nuclear magnetic resonance results confirmed that the EA has successfully replaced Cs + cations to form PEA 2 (Cs 1- x EA x PbBr 3 ) 2 PbBr 4 . This method modulates the photoluminescence from the green region (508 nm) into blue (466 nm), and over 70% photoluminescence quantum yield in blue is obtained. In addition, the emission spectra is stable under light and thermal stress. With configuration of PeLEDs with 60% EABr, as high as 12.1% EQE of sky-blue electroluminescence located at 488 nm has been demonstrated, which will pave the way for the full color display for the PeLEDs. Blue light-emitting diodes (LEDs) are critical for displays. Employing a large organic cation into a quasi-two dimensional perovskite with green emission, Chu et al. achieve LEDs exhibiting a high external quantum efficiency of 12.1% and stable spectra in the sky-blue region.

Device performance and in particular device stability for blue perovskite light-emitting diodes (PeLEDs) remain considerable challenges for the whole community. In this manuscript, we conceive an approach by tuning the ‘A-site’ cation composition of perovskites to develop blue-emitters. We herein report a Rubidium-Cesium alloyed, quasi-two-dimensional perovskite and demonstrate its great potential for pure-blue PeLED applications. Composition engineering and in-situ passivation are conducted to further improve the material’s emission property and stabilities. Consequently, we get a prominent film photoluminescence quantum yield of around 82% under low excitation density. Encouraged by these findings, we finally achieve a spectra-stable blue PeLED with the peak external quantum efficiency of 1.35% and a half-lifetime of 14.5 min, representing the most efficient and stable pure-blue PeLEDs reported so far. The strategy is also demonstrated to be able to generate efficient perovskite blue emitters and PeLEDs in the whole blue spectral region (from 454 to 492 nm). Besides device operational stability, the color stability is also an important challenge for the perovskite light-emitting diodes, especially the blue ones. Here Jiang et al. report the most efficient and color stable pure-blue perovskite LEDs so far, with a half-lifetime of 14.5 minutes.