Search

Comprehensive Summary: As a class of organic dyes, boron‐containing compounds play an important role in organic luminescent materials. They have attracted considerable attention due to their unique photophysical properties. Chiral luminescent systems have a wide range of practical applications in biological imaging, optoelectronic devices, information storage and 3D display. Boron‐containing chiral luminescent materials can not only effectively improve the luminescent properties of CPL materials, but also bring unique properties to the system, which enables them to be used as favorable CPL emitting materials for an expanded range of applications. Here, we review the research progress of boron‐containing chiral luminescent materials by the detailed discuss according to different chiral skeletons, such as point chirality, 1,1'‐binaphthyl, [n]helicenes, [2,2]paracyclophane and pillar[5]arenes. We believe that this review is of significance for the development of boron‐containing compounds and CPL materials. Key Scientists: The studies of circularly polarized luminescence (CPL) based on small organic molecules have advanced significantly. However, boron‐containing chiral luminescent materials have gained attention only in recent years. In 2019, Zhao's group prepared a binaphthalene derivative modified with triarylborane, representing the organic small molecule luminescent material to exhibit CPL characteristics responsive to both solvent and fluoride ions. In 2020, the Chen's group used the unique luminescence properties and steric effects of triarylborane and triphenylamine to prepare CPL materials based on the planar chiral pillar[5]arenes. In 2021, Wang's group developed a new class of B,N‐embedded double hetero[7]helicenes molecules that exhibit strong chiroptical responses in the UV‐visible region. In the same year, He's group used asymmetric reactions to synthesize boron‐based point‐chirality compounds with high efficiency and enantioselectivity. In 2023, Ravat synthesized 1,4‐B,N‐embedded helicenes exhibiting narrow‐band fluorescence and CPL. During this period, Matthias Wagner et al obtained (BO)2‐doped tetrathia[7]helicene via an efficient four‐step synthesis, and Zheng reported the nearly pure green circularly polarized electroluminescent device (CP‐OLED). In 2024, Chen's group prepared B,N‐embedded hetero‐[9]helicenes offering a pathway towards significantly enhanced efficiency in helicene‐based CPEL. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: As a class of organic dyes, boron‐containing compounds play an important role in organic luminescent materials. They have attracted considerable attention due to their unique photophysical properties. Chiral luminescent systems have a wide range of practical applications in biological imaging, optoelectronic devices, information storage and 3D display. Boron‐containing chiral luminescent materials can not only effectively improve the luminescent properties of CPL materials, but also bring unique properties to the system, which enables them to be used as favorable CPL emitting materials for an expanded range of applications. Here, we review the research progress of boron‐containing chiral luminescent materials by the detailed discuss according to different chiral skeletons, such as point chirality, 1,1'‐binaphthyl, [n]helicenes, [2,2]paracyclophane and pillar[5]arenes. We believe that this review is of significance for the development of boron‐containing compounds and CPL materials. Key Scientists: The studies of circularly polarized luminescence (CPL) based on small organic molecules have advanced significantly. However, boron‐containing chiral luminescent materials have gained attention only in recent years. In 2019, Zhao's group prepared a binaphthalene derivative modified with triarylborane, representing the organic small molecule luminescent material to exhibit CPL characteristics responsive to both solvent and fluoride ions. In 2020, the Chen's group used the unique luminescence properties and steric effects of triarylborane and triphenylamine to prepare CPL materials based on the planar chiral pillar[5]arenes. In 2021, Wang's group developed a new class of B,N‐embedded double hetero[7]helicenes molecules that exhibit strong chiroptical responses in the UV‐visible region. In the same year, He's group used asymmetric reactions to synthesize boron‐based point‐chirality compounds with high efficiency and enantioselectivity. In 2023, Ravat synthesized 1,4‐B,N‐embedded helicenes exhibiting narrow‐band fluorescence and CPL. During this period, Matthias Wagner et al obtained (BO)2‐doped tetrathia[7]helicene via an efficient four‐step synthesis, and Zheng reported the nearly pure green circularly polarized electroluminescent device (CP‐OLED). In 2024, Chen's group prepared B,N‐embedded hetero‐[9]helicenes offering a pathway towards significantly enhanced efficiency in helicene‐based CPEL. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Spin crossover (SCO), characterized by distinct high‐spin (HS) and low‐spin (LS) states, has potential applications in memory, electronic, and electroluminescent devices. The OFF/ON switching of SCO is crucial for obtaining bistable magnetic properties. However, there are few strategies for achieving this switching. Herein, based on a ligand chemical doping strategy, we report an Fe(III) solid solution that can be prepared using a ligand chemical doping strategy, enabling not only the OFF/ON switching of SCO but also the fine‐tuning of the spin transition temperature (Tc) within a 45 K range near room temperature. The experimental results show that when the polar ligand doping ratio reaches 20%, SCO behavior is triggered, and the crystal phase transforms significantly, becoming loose and flexible. Furthermore, Tc can be continuously regulated as the ligand‐doping ratio increases. Density functional theory (DFT) calculations reveal that solid packing‐induced molecular distortion blocks SCO, whereas loosely flexible packing triggers SCO via fluorinated ligand chemical doping. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Spin crossover (SCO), characterized by distinct high‐spin (HS) and low‐spin (LS) states, has potential applications in memory, electronic, and electroluminescent devices. The OFF/ON switching of SCO is crucial for obtaining bistable magnetic properties. However, there are few strategies for achieving this switching. Herein, based on a ligand chemical doping strategy, we report an Fe(III) solid solution that can be prepared using a ligand chemical doping strategy, enabling not only the OFF/ON switching of SCO but also the fine‐tuning of the spin transition temperature (Tc) within a 45 K range near room temperature. The experimental results show that when the polar ligand doping ratio reaches 20%, SCO behavior is triggered, and the crystal phase transforms significantly, becoming loose and flexible. Furthermore, Tc can be continuously regulated as the ligand‐doping ratio increases. Density functional theory (DFT) calculations reveal that solid packing‐induced molecular distortion blocks SCO, whereas loosely flexible packing triggers SCO via fluorinated ligand chemical doping. [ABSTRACT FROM AUTHOR]

The development of stable and deformation‐free crystal structures of perovskites and their derivatives are crucial for electroluminescent devices. In this article, a novel transparent manganese‐based perovskite derivative K4MnBr1.33Cl4.67 is synthesized with mixed halogens. For the unique octahedral crystal structure, the Jahn‐Teller distortion, typically present in such structures, is completely suppressed, resulting in high environmental stability of the luminescence spectrum. In transparent flexible devices, the peak current density, average external quantum efficiency on each side and maximum brightness is 45 mA cm−2, 4.9%, and 2800 cd m−2, respectively. The best half‐life of the LED reaches 10 h with a starting luminance of 100 cd m−2. As the first lead‐free transparent flexible perovskite derivative LED, it features an outstanding transparency of 76% and excellent flexibility with a luminescence intensity maintenance of 90% after 2000 bending cycles. This work shows that lead‐free manganese perovskite derivatives can provide a promising way to fabricate stable and high‐performance LEDs. [ABSTRACT FROM AUTHOR]

Excited‐state intramolecular proton transfer (ESIPT) molecules are promising fluorophores for various applications including bioimaging, sensing, and optoelectronic devices. Particularly, their self‐absorption‐free fluorescence properties would make them a perfect choice as emissive materials for organic light‐emitting diodes (OLEDs). Nevertheless, to become effective emitters some of their properties need to be altered by structural modifications. Herein, we design and synthesize a series of new ESIPT molecules (2PImBzP, 2ImBzP, and 2FImBzP) by functionalization of imidazole‐phenol‐based ESIPT cores with electron‐deficient benzo[d]thiazole and various ambipolar imidazole moieties (1‐phenyl‐1H‐phenanthro[9,10‐d]imidazole (PIm), 1,4,5‐triphenyl‐1H‐imidazole (Im), and (4,5‐bis(4‐fluorophenyl)‐1‐phenyl‐1H‐imidazole (FIm)), respectively. Each molecule displays a complete ESIPT process with intense green emissions from a pure keto form and high solid‐state photoluminescence quantum yields (ΦPL) of 65–80 %. These fluorophores with superior thermal stability and balanced charge carrier mobility are effectively employed as non‐doped emitters in OLEDs. The non‐doped devices emit greenish lights with high brightness, high current efficiency (CE) (10.95–17.66 cd A−1), and low turn‐on voltages (2.8–2.9 V). The electroluminescence purely originates from the emission of the keto tautomer of the emissive layers. Specifically, the 2PImBzP‐based non‐doped OLED stands out by achieving a remarkable brightness of 56,220 cd m−2, a CE of up to 17.66 cd A−1, and an impressive external quantum efficiency (EQE) of 5.65 % with a slight efficiency roll‐off. [ABSTRACT FROM AUTHOR]

The formation of core–shell quantum dots (QDs) with type‐I band alignment results in surface passivation, ensuring the efficient confinement of excitons for light‐emitting applications. In such cases, the atomic composition at the core–shell heterojunction significantly affects the optical, and electrical properties of the QDs. However, for InP cores, shell materials are limited to compositions consisting of II–VI group elements. The restricted selection of shell materials leads to an interfacial misfit, resulting in a charge imbalance at the core–shell heterojunction. In this study, the effect of interfacial stoichiometry is investigated on the optical, and electrical properties of InP core–shell QDs. Direct Se injection strategy is employed during the synthesis of the InP core to regulate the interfacial chemical composition, resulting in the formation of an InZnSe alloy on the core surface. This InZnSe layer reduces the misfit between the InP core, and ZnSe shell, leading to a remarkable photoluminescence quantum yield of 95% with a narrow emission bandwidth of 34 nm. The InZnSe interlayer significantly influences the electroluminescence (EL) processes, increasing the charge injection efficiency, and mitigating charge imbalance. A green‐emitting EL device is demonstrated with a maximum luminance of 26370 cd m−2, and a peak current efficiency of 31.5 cd A−1. [ABSTRACT FROM AUTHOR]

Direct electrically pumped organic lasers remain inaccessible to date, due to an interplay of different adverse effects. The most important of these effects are insufficient charge carrier mobility in the organic material, accumulation of triplet excitons upon charge injection, and absorption from the electrodes in the device. While triplet state management can be achieved using molecules that recycle triplet states into emissive singlet states, these molecules rarely support amplified emission. Pyrene derivatives not only show excellent charge transport properties, but their rigid π‐conjugated structure also entails excellent electro‐ and photoluminescence efficiency. Pyrenes exhibit very low‐lying first excited triplet states, rendering this class of molecules interesting for ultrafast upper‐level reverse intersystem crossing. This process counteracts the triplet accumulation in organic lasers. Here, pyrenes are functionalized with electron‐rich moieties of different donor strengths. Through comprehensive spectroscopic and quantum chemical analysis, the character of the charge transfer excited state is correlated with optical properties, excited state lifetimes, amplified spontaneous emission, and triplet recycling. Two donor functionalized pyrenes are reported with violet–blue emission that overcome the spin‐statistical limit of conventional organic emitters with spin factors ηST of up to 0.43 and low thresholds for amplified spontaneous emission Eth down to 1.73 µJ cm−2. [ABSTRACT FROM AUTHOR]

Achieving deep-blue light with high color saturation remains a critical challenge in the development of white light-emitting diode (LED) technology, necessitating luminescent materials that excel in efficiency, low toxicity, and stability. Here, we report the synthesis of [N(C2H5)4]2Cu2I4 (TEA2Cu2I4) single crystals (SCs), which exhibit deep-blue photoluminescence (PL) at 450 nm. These crystals are characterized by a significant Stokes shift of 180 nm, a long lifetime of 1.7 μs, and an impressive photoluminescence quantum yield (PLQY) of 96.7% for SCs and 87.2% for polycrystalline films. The zero-dimensional structure is attributed to the proper spacing of triangular inorganic units [Cu2I4]2− by organic cations [N(C2H5)4]+. This structural arrangement facilitates broadband deep-blue light emission with phosphorescent characteristics, as evidenced by temperature-dependent PL and time-resolved photoluminescence (TRPL) measurements. The band gap properties of TEA2Cu2I4 were further elucidated through density functional theory (DFT) computations. Notably, the material exhibited minimal PL intensity degradation after continuous UV irradiation and one month of exposure to ambient conditions. Moreover, the polycrystalline film of TEA2Cu2I4 maintained substantial deep-blue emission even after one year of storage. Utilizing TEA2Cu2I4 thin film, we fabricated an electroluminescent device emitting deep-blue light with high color saturation, featuring CIE coordinates (0.143, 0.076) and a brightness of 90 cd/m2. The exceptional photophysical properties of TEA2Cu2I4 render it a highly promising candidate for optoelectronic applications. [ABSTRACT FROM AUTHOR]

In a thick-dielectric electroluminescent (TDEL) device, which is a variation of thin-film electroluminescent devices, one of the insulation layers is replaced by a thick-film dielectric layer. High brightness and reliability are the features of TDEL owing to a higher withstanding voltage of the thick-film dielectric layer. This paper presents a new type of TDEL with a bottom emission structure. The thick-film dielectric layer was manufactured by spin coating using an ink material, which is a mixture of BaTiO3 powder and a binder resin. The thicknesses of the phosphor and dielectric layers were minimized to reduce the operating voltage. A threshold voltage as low as 50 V and a maximum luminance of 1000 cd/m2 were obtained at 60 V. [ABSTRACT FROM AUTHOR]

Multi‐resonant thermally activated delayed fluorescence (MR‐TADF) emitters have attracted strong interest for organic electroluminescent devices due to their high photoluminescence quantum yield (ΦPL) and narrowband emission. These properties are also crucial for high‐performance biological probes, especially red emitters. Orange and red MR‐TADF emitters, PhDPA‐DiKTa and MeODPA‐DiKTa, are designed by decorating the DiKTa core with di([1,1′‐biphenyl]‐4‐yl)amine and bis(4‐methoxyphenyl)amine, respectively. As 5 wt.% doped films in 1,3‐di(9H‐carbazol‐9‐yl)benzene (mCP), PhDPA‐DiKTa emits at λPL of 617 nm, while MeODPA‐DiKTa emits at λPL of 655 nm. Both show delayed fluorescence, with delayed lifetimes, τd, of 658.4 and 249.2 µs, respectively. Water‐dispersible glassy organic dots (g‐Odots) based on these materials are prepared by encapsulating them and mCP host into an amphiphilic DSPE‐PEG2k polymer. Both families of g‐Odots showed a deeper red emission and enhanced ΦPL compared to the corresponding 5 wt.% doped films in mCP (λPL = 618 nm, ΦPL = 77% for PhDPA‐DiKTa g‐Odots, λPL = 663 nm, ΦPL = 38% for MeODPA‐DiKTa g‐Odots). The TADF character of the emitters is conserved in the g‐ODots, with τd of 203.9 µs for PhDPA‐DiKTa g‐Odots and 131.6 µs for MeODPA‐DiKTa g‐Odots. These MR‐TADF g‐Odots are successfully demonstrated as biological imaging probes of HeLa cells. [ABSTRACT FROM AUTHOR]

Organic fluorescent emitters based on π-conjugated small molecules show tremendous potential for display, lighting, and bio-imaging applications. However, these emitters face challenges of aggregation-caused quenching and limitations of color range caused by synthetic complexity and undesirable efficiency and quantum yield. In this work, by using quinoxaline/2,1,3-benzothiadiazole as central electron acceptors, and employing carbazole/thiophene/3,4-ethylenedioxythiophene as terminal electron donors, a series of π-conjugated fluorescent trimers with very low molecular weights (Mw = 294–466) were designed and synthesized. Modulating the molecular structure through the incorporation of distinct electron donor and acceptor moieties, broad spectral tuning from blue to red in the π-conjugated trimers was achieved. These conjugated trimers when applied as emitting layers in electroluminescent devices, particularly organic light-emitting diodes (OLEDs), exhibit high brightness and color-tunable electroluminescence (EL) peaks from 528 to 605 nm. The meticulously optimized device demonstrates excellent performance with a high brightness of 3857.19 cd m−2, and an external quantum efficiency (EQE) of 2.29%. These π-conjugated trimers, synthesized by a simple synthesis process, present a viable avenue for low-cost luminescence lighting and display applications. [ABSTRACT FROM AUTHOR]

Aiming to design new efficient organic triplet emitters, here a new electron‐accepting moiety 11,13‐dihydro‐12H‐dibenzo[a,c]imidazo[4,5‐i]phenazin‐12‐one (BIPO) are reported. Three new BIPO derivatives containing long alkyl chains, namely DBIPO (acceptor only), DBIPOBr (acceptor containing bromine atoms), and DBIPOAc with acridan moieties in a donor‐acceptor‐donor configuration, are designed and investigated. Efficient room temperature phosphorescence (RTP) is detected for the three compounds, stemming from a high‐lying (anti‐Kasha type) triplet emission occurring in the acceptor moiety. Additionally, the tetrahydrofuran‐ and dichloromethane DBIPOAc solutions show (i) a dual‐band photoluminescence profile stemming from anti‐Kasha emissions from high‐lying charge‐transfer (1CT) and locally excited (1LE) states, and (ii) a thermally activated delayed fluorescence (TADF) from the same high‐lying 1CT state. Importantly, DBIPOAc doped in rigid nonpolar polymer Zeonex simultaneously exhibits both TADF and RTP, with the emission quantum yield reaching 69.6%. Due to these properties, the BIPO derivatives constitute promising candidates as multi‐functional new emitters for the preparation of active layers of electroluminescent devices and optical oxygen/pressure sensors. The reasons for these interesting properties are discussed in detail. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals are attractive for light emitting devices both as electroluminescent and color‐converting materials since they combine intense and narrow emissions with good charge injection and transport properties. However, while most perovskite nanocrystals shine at green and red wavelengths, the observation of intense and stable blue emission still remains a challenging target. In this work, a method is reported to attain intense and enduring blue emission (470–480 nm), with a photoluminescence quantum yield (PLQY) of 40%, originating from very small CsPbBr3 nanocrystals (diameter < 3 nm) formed by controllably exposing Cs4PbBr6 to humidity. This process is mediated by the void network of a mesoporous transparent scaffold in which the zero‐dimensional Cs4PbBr6 lattice is embedded, which allows the fine control over water adsorption and condensation that determines the optimization of the synthetic procedure and, eventually, the nanocrystal size. The approach provides a means to attain highly efficient transparent and stable blue light‐emitting films that complete the palette offered by perovskite nanocrystals for lighting and display applications. [ABSTRACT FROM AUTHOR]

Organic ultralong room temperature phosphorescence (OURTP) materials capable of combining various emission behaviors for diversified optoelectronic properties and applications have recently gained a vigorous development, but it remains a forbidden challenge in designing OURTP molecules with hybrid local and charge‐transfer (HLCT) feature, possibly due to the elevated difficulties in simultaneously meeting the stringent requirements of both HLCT and OURTP emitters. Here, through introducing multiple heteroatoms into one‐dimensional fused ring of coumarin with moderate charge transfer perturbation in donor‐π‐acceptor architecture, we demonstrate a HLCT‐featured OURTP molecule showing both promoted fluorescence with a quantum yield of 77 % in solution and long‐lived OURTP with a lifetime of 251 ms in conventional host material used in electroluminescent device. Thus, efficient OURTP organic light‐emitting diodes (OLEDs) were fabricated, exhibiting bright electroluminescence with an exciton utilization efficiency of 85 % and yellow OURTP lasting over 2 s for afterglow. Impressively, the HLCT OURTP‐OLEDs can be further optimized to reach an unprecedented total external quantum efficiency (EQE) of ~12 % and OURTP EQE up to 3.11 %, representing the highest performance among the reported OURTP‐OLEDs. These impressive results highlight the significance to fuse HLCT and OURTP together in enriching OURTP materials and improving the afterglow OLED performances. [ABSTRACT FROM AUTHOR]

Stretchable electroluminescent (EL) devices have been studied for more than 10 years, and their EL and mechanical performance, such as brightness, efficiency, stretchability, and stretching stability show significant improvement. Stretchable display is considered to be the most promising next‐generation display technology, which has broad application prospects in various emerging fields, such as deformable displays, electronic skins, and biomedical devices, and it attracts much attention from worldwide manufacturers. However, no commercial application cases for stretchable displays are reported to date. There are many reasons for this situation, including deficient device performance, immature preparation process, and diversiform device structures and materials. On the other hand, although researchers devise a number of possible applications for stretchable EL devices, it is still controversial what unique and interesting functions stretchable displays can play in these scenarios, and whether they can be replaced by flexible, bendable, and rollable devices with better EL and mechanical performance. Therefore, the future of stretchable displays is full of both opportunities and challenges. In response to the above concerns, this review summarizes the characteristics, problems, and possible solutions of various types of stretchable EL devices, aiming to promote their development and application. [ABSTRACT FROM AUTHOR]

Hot exciton emitters based on 9,10‐substituted anthracenes are a well‐investigated class of molecules featuring thermally activated delayed fluorescence (TADF). TADF converts triplet excitons into singlet excitons and improves the internal quantum efficiency of electroluminescent devices to performance beyond the limit of spin‐statistics of conventional emitters. In this paper, we compare different 1,8‐functionalized donor/acceptor‐substituted anthracenes and compare these to established 9,10‐functionalized hot exciton emitters. Interestingly, our new 1,8‐substituted anthracenes make use of a beneficial hot exciplex pathway, resulting in improved emission characteristics and higher photoluminescence quantum yield. [ABSTRACT FROM AUTHOR]

The quest for stretchable properties is at the forefront of research dedicated to on‐skin light–emitting devices. Inspired by the natural wonders of bioluminescence, electrochemiluminescent devices (ECLDs) are distinguished by straightforward design and reduced operating voltage, marking a departure from traditional current‐driven electroluminescent devices (ACELDs). The primary challenge of fully‐stretchable ECLDs lies in crafting electrodes that simultaneously satisfy the demands for conductivity, transparency, stretchability, oxidation resistance, and interface stability. This research introduces a groundbreaking wrinkled polymer‐gold composite electrode. It extends to 50% stretchability, offers outstanding conductivity at 10 Ω sq−1, achieves transparency above 60%, and withstands over 10 000 stretching cycles. Employing this material, alongside stretchable electrospinning fiber luminescent layers, enabled the creation of fully‐stretchable ECLDs. These devices not only shine brightly at 30 Cd m−2 but also retain more than 90% of luminosity when stretched up to 50%. Furthermore, this work has engineered stretchable devices featuring singular patterns and multi‐dot arrays. They exhibit consistent luminescent output under bending, twisting, and stretching when applied to skin. These findings not only highlight the potential of polymer‐gold composite electrodes in overcoming challenges faced by stretchable electronic devices but also provide new ideas for wearable technology that seamlessly integrates with human body. [ABSTRACT FROM AUTHOR]

Stretchable dielectric polymer with high dielectric constant is a major component for electroluminescent devices. However, the intrinsic instability toward water severely limits their further applications in marine environment. Here, a transparent, underwater stable, and self‐healable dielectric material with high dielectric constant is reported. The electroluminescent device based on this newly designed fluoropolymer can work stably in aqueous conditions. There is no significant attenuation of mechanical and optoelectronic property after immersed in water and salty water for a month. The intrinsic self‐healing ability of the device makes it robust and resilient against unexpected minor or severe damages. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) molecules are regarded as promising materials for realizing high‐performance organic light‐emitting diodes (OLEDs). The connecting groups between donor (D) and acceptor (A) units in D–A type TADF molecules could affect the charge transfer and luminescence performance of TADF materials in aggregated states. In this work, we design and synthesize four TADF molecules using planar and twisted linkers to connect the aza‐azulene donor (D) and triazine acceptor (A). Compared with planar linkers, the twisted ones (Az‐NP‐T and Az‐NN‐T) can enhance A–A aggregation interaction between adjacent molecules to balance hole and electron density. As a result, highly efficient and stable deep‐red top‐emission OLEDs with a high electroluminescence efficiency of 57.3% and an impressive long operational lifetime (LT95 ∼ 30,000 h, initial luminance of 1000 cd m−2) are obtained. This study provides a new strategy for designing more efficient and stable electroluminescent devices through linker aggregation engineering in donor–acceptor molecules. [ABSTRACT FROM AUTHOR]

The Special Issue of Micromachines, titled "Nanomaterials for Micro/Nanodevices," explores the advancements and applications of nanomaterials in micro- and nano-scale devices. The issue features ten papers that highlight the unique properties of nanomaterials and their role in enhancing device performance. From bio-inspired nanomaterials to superhydrophobic surfaces and novel materials like nanostructured spinel chromites, the issue covers a wide range of topics that showcase the potential of nanomaterials in driving future technological innovations. Researchers and practitioners can gain valuable insights from these studies to further develop nanomaterial applications in various fields. [Extracted from the article]

Near ultraviolet (NUV) organic light‐emitting diodes (OLEDs) have great advantages in the field of light excitation sources, chemical and biological sensors, etc. However, the molecular design of NUV emitters still faces the challenges of spectral broadening and red‐shift. In this study, attaching weak oxygen‐bridged triarylboron acceptor to weak carbazolyl donor is able to address intractable problems by weakening donor–acceptor (D–A) charge transfer. Simultaneously, sterically wrapped and modified oxygen‐bridged triarylboron acceptor by bulk substituents (multiple carbazolyl) can suppress intermolecular π–π stacking through steric hindrance effect. These design strategies are able to obtain short‐wavelength, narrow‐band emission, and great color purity. As a result, carbazolyl derivatives xCz‐BO‐based (x = 2, 3, 4, 5) emitters show EL emission peaks from 406 to 422 nm in the NUV light region and small full‐width at half‐maximums (FWHMs) of 32–41 nm over a wide range of dopant concentrations (10–40 wt.%). The most violet Commission International de I'Eclairage (CIE) color coordinate is (0.16, 0.03). Moreover, 5Cz‐BO can be employed as host for vacuum‐/solution‐processed blue OLEDs and these devices exhibit high performance with EQEs of over 20%. [ABSTRACT FROM AUTHOR]

Bulk γ‐InSe has a direct bandgap of 1.24 eV, which corresponds to near infrared wavelengths (λ = 1.0 µm) useful in optoelectronic applications from biometric detectors to silicon photonics. However, its potential for optoelectronic applications is largely untapped due in part to the lack of quantitative studies of its optical properties. Here, the unusually low absorptance and high photoluminescence quantum efficiency of single‐crystalline InSe flakes with thickness in the hundreds of nanometers are studied. InSe emits brightly at room temperature from its direct bandgap with a peak photoluminescence quantum yield (PLQY) of 20%, despite displaying indirect bandgap like low absorption coefficient due to the symmetry of its crystal structure. By performing pump‐dependent PLQY measurements, the radiative and nonradiative recombination coefficients are extracted, including the Shockley‐Read‐Hall and Auger coefficients. Finally, a proof‐of‐concept alternating current electroluminescent device at low temperature is demonstrated to show the promise of InSe in optoelectronic technology such as highly transparent, bright NIR light sources. [ABSTRACT FROM AUTHOR]

The emergence of planar electroluminescent diodes (including polymer light‐emitting diodes, organic light‐emitting diodes, quantum‐dot light‐emitting diodes, and perovskite light‐emitting diodes) is causing a revolution in displays, lighting, and wearable electronic devices. Continuous advancement in the comprehension and management of charge carrier dynamics in these devices has led to several significant breakthroughs, including diodes with ultrahigh luminance, memory devices, and amplified spontaneous emission. Transient electroluminescence (TrEL) spectroscopy is a relative powerful technology to investigate charge dynamics, including transport, distribution, and storage of charge carriers, in electrically‐driven planar light‐emitting diodes (LEDs). The aim of this review is to revisit the principle and applications of TrEL spectroscopy in planar electroluminescent diodes, and to evaluate the reliability of various parameters extracted using this technology. A particular focus is on electroluminescence response time, charge‐carrier transport and storage, and exciton species. First, the principle and equipment system of the TrEL, as well as specific attention during TrEL measurements are described in detail, following by the applications TrEL spectroscopy in planar LEDs. Further development on the TrEL technology is discussed in the third section. Finally, a summary and outlook for the TrEL are shown and challenges faced by the TrEL spectroscopy are also highlighted. [ABSTRACT FROM AUTHOR]

Flexible and stretchable ion‐conductive elastomers have shown promising applications in wearable flexible sensor devices, biopotential detection, electroluminescent devices, and other areas. However, the currently employed gel‐based ion‐conductive materials encounter issues such as solvent volatilization or leakage. Herein, there is an urgent requirement to develop a solid‐state ionic conductor material that is both safe and reliable, free from issues of liquid leakage. Here, the study reports a solid‐state ion‐conductive elastomer with excellent mechanical properties and high ionic conductivity based on a synergistic strategy of multiple interaction forces. The solid‐state ion−conductive elastomer exhibits high ionic conductivity (1.42 × 10−4 S cm−1 at 25 °C), superior stretchability (≈1550% elongation) and strength (1.48 MPa). Moreover, the solid‐state ion‐conductive elastomer exhibits high resilience and possesses excellent self‐healing ability. The wearable sensor, prepared based on the solid‐state ion‐conductive elastomer with excellent comprehensive performance, not only demonstrates high strain sensitivity but also captures high‐quality epidermal biopotential signals from the human body in biopotential detection. Additionally, the solid‐state ion‐conductive elastomer can serve as an electrode in ionic electroluminescent devices for human wearable applications. It is believed that the solid‐state ion‐conductive elastomer can provide novel opportunities for the advancement of wearable devices and soft ionotronics. [ABSTRACT FROM AUTHOR]

Excited-state intramolecular proton transfer (ESIPT) materials have emerged as highly promising candidates for emitters in organic light-emitting diodes (OLEDs), attributed to their distinctive photophysical properties. These materials have garnered considerable attention due to their pronounced Stokes shifts, exceptional color purity, and potential for achieving high efficiency and stability in OLED applications. To develop highly luminescent solids with large Stokes shifts, two imidazole-based ESIPT-AIE emitters, PPy-HPI and PPy-HPIC, have been synthesized following the strategy of combining excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) systems. These emitters integrate the ESIPT cores 2-(2-hydroxy-5-methylphenyl)-1,4,5-triphenylimidazole (HPI) and 2-(2-hydroxy-5-methylphenyl)-1- phenylphenanthroimidazole (HPIC) with the AIE-active luminogen 4-(1-phenylvinyl)pyridine (PPy). The ESIPT and AIE properties were confirmed through both theoretical and experimental studies. The emitters demonstrated ESIPT and AIE characteristics, featuring a large Stokes shift and strong yellow-green to yellow emission in the solid state, which originated from the pure keto form. A non-doped OLED utilizing PPy-HPIC demonstrated yellow emission with CIE coordinates of (0.47, 0.51), a maximum external quantum efficiency (EQEmax) of 3.13% and a maximum current efficiency (CEmax) of 9.48 cd A-1. Notably, the non-doped OLED incorporating PPy-HPI exhibited yellow-green emission with CIE coordinates of (0.15, 0.10), EQEmax of 3.61%, and CEmax of 10.56 cd A-1, with minimal efficiency roll-off. These results signify a major breakthrough in creating ESIPT molecules for use as non-doped emitters in fluorescent OLEDs. [ABSTRACT FROM AUTHOR]

Photonic elements have greater information‐carrying capabilities compared to electronic components, making the development of high‐speed, chip‐integrated optical communication devices crucial for addressing interconnect bottlenecks in high‐speed computing systems. Significant progress has been made in studying light sources and their transmission. Despite these advancements, achieving a satisfactory integration of photonic circuits with both light source and optical waveguide functions has remained a challenge. Here, a silver nanowire (AgNW) waveguide‐integrated light source is demonstrated driven by alternating current (AC) voltage. AgNW functions as both the electrode and waveguide to simplify the device structure, and the 2D transition metal dichalcogenides (TMDs) monolayer acts as the gain media in device. The electroluminescence (EL) can be tunably modulated via adjusting the frequency and voltage of the AC in this device, and it is also successfully coupled into the waveguide with its transmission distance up to 25 µm. The experiments of electroluminescence and waveguide transmission of different materials and their interlayer excitons have made a preliminary exploration of multiple wavelength transmission. It provides a new research platform forward in the development of chip‐integrated optical communication devices, thereby hopefully addressing the interconnect bottleneck and unlocking the potential for enhanced performance and efficiency in high‐speed computing systems. [ABSTRACT FROM AUTHOR]

Lanthanide ions doped in perovskite (LIDP) nanocrystals (NCs) provide an effective way to utilize the emission of lanthanide metals in a solution‐processable way, combining the theoretical photoluminance quantum yield (PLQY) of ≈200%. To utilize advantages, LIDP‐NCs have inspired studies exploring the fundamental physics of energy transfer, including the up‐conversion or down‐conversion process, and the optoelectronic applications of solar cells and white light‐emitting didoes. This review broadens the scope of LIDP nanocrystal matrix semiconductors in electroluminescence devices in the near‐infrared (NIR) range (>900 nm). A research is summarized on the synergistic effect of lanthanide ions and perovskite matrix in the near‐infrared region, and discuss from the perspective of fabrication of lanthanide‐based electroluminescent devices using perovskite materials as the matrix. The multiple optical transitions, bandgap tunability, and quantum‐cutting effect to provide a tutorial on understanding LIDP‐NCs are started. The details of synthesizing LIDP materials and aim to lay the foundation for preparing NIR electroluminescent devices with high efficiency and application value are then illustrated. The scientific issues that limit the performance of LIDP NCs‐based electroluminescent devices and discuss the potential strategies for the future development of LIDP material are focused on. [ABSTRACT FROM AUTHOR]

Large-area imaging techniques in the short-wave infrared spectral region remain a pressing need. Organic light-emitting diodes and infrared photodetectors can be combined to form a near-infrared (NIR) to visible upconversion device, which has great potential to replace traditional infrared imaging systems. The integration of a white organic light-emitting diode (WOLED) with infrared photodetectors has become essential to realize full-color displays for its simple preparation process and high compatibility. This work has designed and optimized a WOLED to achieve stable emission with high brightness (19 470 cd m−2) and high external quantum efficiency (EQE = 18.08%) at a wide voltage range, thereby reducing chromaticity drift caused by voltage fluctuations. Moreover, photon-generated holes in the NIR-sensitive photodetector are able to inject into the WOLED for visible light emission. Consequently, we have obtained a high-performance upconversion device with a luminance on-off ratio exceeding 5 × 103 at 850 nm NIR and a high color stability over a wide range of operating voltage. Our efforts have accomplished a high-performance upconversion device from NIR to white visible light, laying the groundwork for a preliminary exploration of full-color displays. [ABSTRACT FROM AUTHOR]

Energy level alignments are crucial for designing high-performance semiconductor devices. However, the reported energy levels, especially the lowest unoccupied energy levels (LUMOs), exhibit significant variability for a given molecular compound. This variability often leads to misunderstanding of device working mechanisms. In this study, single-carrier devices with organic/interlayer/organic structures are proposed to probe the energy level alignments at organic–organic heterojunctions. It is observed that carrier transport characteristics deviate significantly depending on charge scattering or trapping. Five organic molecules, including 1, 3, 5-tri(m-pyrid-3-ylphenyl)benzene (TmPyPB), 4, 4′-bis(arbazole-9-y1)biphenyl (CBP), 2, 2′, 2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), bis[2-(2-hydroxyphenyl)-pyridine] beryllium (Bepp2), and tris(8-hydroxyquinolinato)aluminum (Alq3), are utilized to test the method. The deduced LUMO level order for these materials is found to deviate significantly from reported values. Furthermore, the effect of differences in the energy level arrangement on the performance of electroluminescent devices is investigated. This work suggests that determining LUMO energy alignments via single-carrier analysis is a valuable method for understanding device working mechanisms. [ABSTRACT FROM AUTHOR]

Elastomers based on cross‐linked bottlebrush polymers combine an extreme softness at low strains with a strain‐stiffening effect, which makes them attractive as active components in dielectric elastomer actuators (DEA). Their main disadvantage concerns the small relative permittivity, which is about 3.5, requiring relatively high driving voltage in actuators. We synthesized a bottlebrush polymer elastomer with polar brushes, which exhibit an enhanced dielectric permittivity of 4.4. Anionic ring‐opening polymerization of a polar cyclosiloxane gave telechelic polar brushes, while ring‐opening polymerization of a norbornene macromonomer gave a bottlebrush polymer which was cross‐linked to elastomers by a thiol‐ene reaction. Elastomers with a small elastic modulus below 100 kPa, strain at break exceeding 100 %, attractive elasticity, and small mechanical loss factors (tanδ) were achieved. Temperature‐dependent impedance measurements revealed a transition temperature of −95 °C and an interfacial polarization. The multigram scale synthesis demonstrates the potential for scaling up, which opens the door to broader applications of these materials beyond actuators, such as capacitive sensors, batteries, and electroluminescent devices. Notably, these devices operate at extremely low voltages where the dielectric breakdown does not limit their functionality, but still, the softness and the increased dielectric permittivity are a plus. [ABSTRACT FROM AUTHOR]

Triplet‐triplet annihilation upconversion (TTA‐UC) has made significant progress in recent years in several key applications, including solar energy harvesting, photocatalysis, stereoscopic 3D printing, and disease therapeutics. In TTA‐UC research, photosensitizers serve the vital function of harvesting low‐energy photons. The photophysical characteristics of photosensitizers, including absorbance, triplet state quantum yield, triplet state energy level, triplet state lifetime, etc. determine the performance of TTA‐UC. Thus, the study of photosensitizers has been a key aspect of TTA‐UC. In recent years, multi‐resonance thermally activated delayed fluorescence (MR‐TADF) molecules have received extensive attention due to their excellent photophysical properties and electroluminescent device performance. MR‐TADF molecules not only present a narrow energy gap between the singlet and triplet excited states, but also have stronger absorption and better wavelength regulation than conventional TADF molecules. Nowadays, the preliminary attempts in TTA‐UC using MR‐TADF molecules as photosensitizers have resulted in the development of green to ultraviolet, blue to ultraviolet, and even near‐infrared to blue emission. This concept will summarize the research progress of MR‐TADF molecules as photosensitizers in TTA‐UC, analyzing the challenges and giving possible solutions. Finally, we prospect the future development of MR‐TADF molecules as photosensitizers, including the molecular design as well as the possible application areas. [ABSTRACT FROM AUTHOR]

In today's rapidly evolving technological landscape, electroluminescent devices have emerged as pivotal components, illuminating a path toward energy‐efficient lighting solutions, advanced displays, and integrated sensing technologies, profoundly impacting sectors ranging from consumer electronics to sustainable urban development. Based in such socio‐scientific‐economic scenario, and in the pursuit of sustainable and environmentally conscious technologies, this work presents a novel approach to the development of a multifunctional electroluminescent (EL) device capable of both efficient lighting and electric field frequency sensing applications. The proposed device integrates a composite based on zinc sulfide co‐doped with copper (ZnS:Cu) phosphor particles and plant‐based UV resin, to achieve enhanced functional properties and reduced environmental impact. The developed anycubic plant‐based UV resin clear (ECOr)/ZnS:Cu inks display viscosity values between 0.5 and 100 Pa.s (ensuring good quality of screen‐prints), and after printing composites exhibit thermal stability up to ≈200 °C; morphological homogeneity, dielectric properties dependent on the ZnS:Cu content (dielectric constant of 12.8 for the sample with 80 wt.% of filler); 30 cd.m2 luminance for the sample with 80 wt.% of ZnS:Cu; and colorimetric electric field frequency sensing capability in the 0–3 kHz range. Thus, this research contributes to the advancement of sustainable technologies that prioritize both multifunctionality and environmental responsibility in the fabrication of electroluminescent devices for lighting and sensing. [ABSTRACT FROM AUTHOR]

While the development of solution‐processed organic light‐emitting diodes (sOLEDs) utilizing multiple resonance‐induced thermally activated delayed fluorescence (MR‐TADF) is highly significant, it is restricted by the limited solubility and film‐forming property resulting from the rigid conjugate and planarity of MR‐TADF materials. Herein, an effective strategy is presented to obtain solution‐processed narrowband emitters by introducing an inert steric bulky hindrance group into the multiple resonance skeleton, thereby mitigating issues arising from intermolecular packing‐induced poor solution processing ability and quenching effects. The resulting target emitter, designed as 3CzSF‐BN, exhibits pure‐green emission with a peak at 520 nm and a small full width at half maximum (FWHM) of 30 nm (0.14) eV. Remarkably, it achieves an exceptional photoluminescence quantum yield (PLQY) of 100% and notable advancements in solution processing attributes. The optimized bottom‐emitting sOLED (BE‐sOLED) device achieves an external quantum efficiency (EQE) over 20% with Commission Internationale de I'Éclairage (CIE) coordinates of (0.214, 0.716). Notably, the top‐emitting sOLED (TE‐sOLED) device exhibits an ultra‐pure green color with FWHM of 22 nm and CIE coordinates of (0.138, 0.771), thereby highlighting the effectiveness of this strategy in designing high‐performance solution‐processed MR‐TADF materials. [ABSTRACT FROM AUTHOR]

A new narrowband thermally activated delayed fluorescence emitter, PhCzBN-PO, was developed by incorporating the diphenylphosphine oxide (DPPO) group into a multi-resonance core. The unique properties of DPPO enabled PhCzBN-PO to achieve pure green emission and a nonplanar structure. The resulting electroluminescent devices achieved high external quantum efficiencies up to 32.4% with extremely low efficiency roll-off and pure-green emission with Commission Internationale de L'Eclairage (CIE) coordinates of (0.24, 0.67). [ABSTRACT FROM AUTHOR]

Organic and inorganic hybrid perovskites are a class of solution‐processable semiconductors that hold significant promise for light‐emitting diode applications. However, the development of efficient blue perovskite light‐emitting diodes (PeLEDs) has remained a critical challenge. Although significant advancements have been achieved in the development of sky‐blue PeLEDs, the performance of pure‐blue and deep‐blue PeLEDs still lags. In this manuscript, by incorporating 1‐cyclohexene‐1‐ethanamine cation (CEA+) into the host 1‐phenylbutylamine cation (PBA+) spacer and fabricating mixed‐cations quasi‐2D perovskites, a homogeneous phase distribution in quasi‐2D perovskite films is achieved through precise tuning of the phase formation energy. The resulting PeLEDs exhibit remarkable performance with an external quantum efficiency (EQE) of 5.8% at 467 nm, which is one of the highest EQEs among the deep‐blue light quasi‐2D PeLED devices with emission wavelengths below 470 nm, Additionally, the device demonstrates a half‐lifetime of ≈ 25 min. Furthermore, the PeLEDs utilizing mixed‐cation perovskite exhibit a stable electroluminescence (EL) spectrum under varying voltage biases, even when the chlorine content in the halogen sites reaches as high as 30%. Overall, this work offers a novel and promising avenue to achieve both high EQE and a stable EL spectrum in blue‐light quasi‐2D PeLEDs. [ABSTRACT FROM AUTHOR]

Stretchable alternating current electroluminescent (ACEL) devices have a bright future in wearable electronics and soft robotics. Still, their market application is hindered by high operating voltages. The voltage can be reduced by increasing the relative permittivity of the dielectric elastomer in the emissive layer. Here, a fluorine‐free high‐permittivity silicone elastomer functionalized with cyanopropyl side groups, specially designed for application in stretchable ACEL devices, is introduced. The polar silicone elastomer exhibits excellent mechanical properties and a dielectric permittivity four times higher than commercial PDMS. Light‐emitting devices based on the polar elastomer reach 7.5 times higher maximum luminance at the same electric field than PDMS‐based devices and turn on at a 50% lower electric field. Besides, the polar elastomer‐based devices perform better than all materials tested in literature in achieving high luminance at low electric fields. Stretchable ACEL devices are built from the polar elastomer which shows bright and uniform light emission and can be operated up to 50% strain. The high‐permittivity silicones are promising materials for stretchable ACEL devices and can help their breakthrough to market application by overcoming the drawback of high operating voltages. [ABSTRACT FROM AUTHOR]

Electroluminescent (EL) devices are of great significance for expanding the application range of optoelectronics. However, the realization of EL devices with environment-tolerance, stretchability, mechanical cycling stability, self-adhesion, biocompatibility, and high dielectric constant still remains a challenge. Herein, a type of EL device with enhanced comprehensive performances composing of a chlorinated barium titanate/phosphor/polydimethylsiloxane (Cl-BT/phosphor/PDMS) luminescent layer sandwiched between two silver nanowire-cellulose nanocrystal with II crystalline allomorph/Triton X-100 modified polydimethylsiloxane (AgNW-CNC II/TX-PDMS) electrodes fabricated through a full solution-processing strategy is proposed. Environmentally-friendly CNC II with high transmittance acts as an antioxidant, dispersant and film-former for AgNWs. The hydrophilic modification of TX to PDMS imparts the electrodes with self-adhesion, high stretchability, as well as strong interfacial bonding between TX-PDMS and AgNW-CNC II. The electrodes achieve skin-like modulus by adjusting TX content, endowing the EL devices with a high compliance (186 kPa of Young's modulus). The luminescent layer with Cl-BT exhibits a high dielectric constant (19) and luminance (up to 72 cd m−2). The assembled EL device with excellent cyclic stability (luminance retention 85% after 400 cycles), durability (luminance retention >94% after 400 min) and stretchability (88% luminance at 200% strain) can work properly at broad temperatures (−20 ~ 70 °C) and underwater. This biocompatible and self-adhesive EL device demonstrates great potential for implantable biomedical devices and wearable displays under harsh environments. [ABSTRACT FROM AUTHOR]

Circularly polarized electroluminescent devices are conventionally fabricated by incorporating an optically active chiral luminophore into their emission layer. Herein, we developed a circularly polarized perovskite light-emitting diode (PeLED) system with an optically inactive perovskite luminophore that can emit near-infrared circularly polarized electroluminescence (CPEL) upon application of an external magnetic field. The magnitude of the magnetic CPEL (gMCPEL) was in the order of 10−3 in the near-infrared wavelength range of 771–773 nm. Although the Pb perovskite quantum dots were achiral, the rotation direction of the CPEL of the magnetic circularly polarized PeLED system was successfully reversed by switching the Faraday geometry of the applied magnetic field. The use of achiral luminophores exhibiting magnetic-field-induced CPEL represents a new approach for the development of circularly polarized electroluminescent devices. [ABSTRACT FROM AUTHOR]

We are introducing an innovative organic semiconductor electroluminescent device capable of emitting light with unprecedented characteristics: high directionality (divergence angle of 1.1°) and high color purity (full width at half‐maximum of 2.5 nm). This achievement was realized through intricate design techniques aimed at enhancing gain via meticulous recombination zone control, complemented by the reduction of losses through minimizing the overlap of the optical mode with the electrodes. These groundbreaking results mark the world's first demonstration of simultaneously achieving a narrow spectrum and superior directionality in an organic electroluminescent device. [ABSTRACT FROM AUTHOR]

The nanoLED, an electroluminescent device utilizing quantum dots (QDs), is expected to be a promising candidate for the next‐generation display. This paper presents a newly developed QD protection technology for cadmium‐free nanoLEDs that enables simultaneous achievement of high‐efficiency electroluminescence (EL) and long lifetime. The device which was prototyped by applying ZnSeTe blue QDs to an emissive layer demonstrated a maximum external quantum efficiency (EQE) of 21.0% and a luminance half‐lifetime (LT50) of 128,000 hours at 100 nits. These results indicate that cadmium‐free nanoLEDs can meet the requirements for display application in terms of both EL efficiency and reliability. [ABSTRACT FROM AUTHOR]

Organic–inorganic perovskite (OIP) nanoparticles exhibit excellent luminescence properties and photovoltaic efficiency and can be used in bulk and thin films. In this study, a mechanically robust OIP quantum dot dispersion layer was deposited on glass substrates via a rapid synthesis process. First, hierarchical nanoporous structures with a thickness of 1.5 μm were formed on the glass surface. These structures were dipped in a precursor liquid and then dried. Thereafter, OIP crystals of methylammonium lead bromide (MAPbBr 3) with sizes of 5–10 nm were precipitated inside nanopores. The low-temperature luminescence properties of the obtained samples at 4–110 K were compared with those of spin-coated films and bulk MAPbBr 3. The emission peak wavelength of the sample precipitated in the nanopores on the glass surface (with an energy of 2.16 eV) was lower than that of the bulk sample (with an energy of 2.01 eV), and its luminescence intensity was two orders of magnitude higher than that of the bulk sample. The proposed method can be used to fabricate solar cells, electroluminescent devices, and scintillators. [ABSTRACT FROM AUTHOR]

We are introducing an innovative organic semiconductor electroluminescent device capable of emitting light with unprecedented characteristics, that is, high directionality with divergence angle of 1.1° and high color purity with the full‐width at half‐maximum of 2.5 nm. This achievement was realized through design techniques aimed at enhancing gain via meticulous recombination zone control and complemented by the reduction of the optical losses. These results demonstrate the simultaneous achievement of a narrow spectrum and high directionality in an organic electroluminescent device. [ABSTRACT FROM AUTHOR]

Electroluminescence (EL) is an innovative technology in the lighting area. EL devices' main structure consists of a phosphor layer sandwiched between two electrodes. In this work, several alternating-current EL devices were developed by applying a set of sequential layers with combinations of in-house prepared inks and a commercially available ink as the phosphor layer. A flexible polyester textile substrate was functionalized with the inks by spray coating, after knife coating an interfacial layer directly on the surface. A thorough study was carried out on the phosphor layer composition to optimize the EL device performance, more precisely, illuminance intensity and illuminance homogeneity. The developed phosphor layer was composed of zinc sulfide doped with copper (between 30.0 and 38.1 wt%) and diluted by using a diluent at different concentrations (from 28.0 to 35.5 wt%). The best peak illuminance intensity of 61 lux was obtained when the phosphor ink presented a 35.4% ZnS:Cu ratio and was diluted with 33.0% diluent. This study aimed to determine the best formulation of the phosphor layer, which can be highly useful for further developments of EL devices, taking into account different applications in the market. [ABSTRACT FROM AUTHOR]

Soft robots require soft actuators for mobility and functionality. To integrate multiple functions in a limited space, researchers are developing multifunctional soft actuators with several functions integrated in one device. This study successfully demonstrates an electroluminescent (EL) soft actuator, a single device with both light‐emitting and actuating capabilities, using liquid dielectric and uniformly dispersed EL phosphor particles. EL phosphor particles are copper‐doped zinc sulfide (ZnS) particles doped with copper. The work is able to disperse the ZnS particles uniformly in the oil by coating the ZnS particles with silica, ensuring consistent luminescence across the device's active area. The performance of the soft actuator is notable, with a strain of 25% and a maximum EL intensity of 23 cd m−2 for a single actuator. When stacking multiple actuators, the intensity exceeds 29 cd m−2. The findings suggest that EL actuator devices will be valuable smart components for soft robots and interactive sensors. They can effectively represent external stimuli through color signals, expanding the capabilities of these systems. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to review the research progress in the realization of the organic–inorganic hybrid thin-film packaging of flexible organic electroluminescent devices using the PEALD (plasma-enhanced atomic layer deposition) and MLD (molecular layer deposition) techniques. Firstly, the importance and application prospect of organic electroluminescent devices in the field of flexible electronics are introduced. Subsequently, the principles, characteristics and applications of PEALD and MLD technologies in device packaging are described in detail. Then, the methods and process optimization strategies for the preparation of organic–inorganic hybrid thin-film encapsulation layers using PEALD and MLD technologies are reviewed. Further, the research results on the encapsulation effect, stability and reliability of organic–inorganic hybrid thin-film encapsulation layers in flexible organic electroluminescent devices are discussed. Finally, the current research progress is summarized, and the future research directions and development trends are prospected. [ABSTRACT FROM AUTHOR]

Exploiting narrow-bandwidth-emission fluorescent materials is crucial for next-generation wide-color gamut displays. Inspired by the narrow-bandwidth-emission characteristic of chlorophyll derivates, the present work develops a facile strategy to synthesize a series of red-emitting chlorophyll-structured CDs (CHL-CDs) with ultra-high color purity and good carrier mobility from different traditional Chinese medicine leaves through a simple cross-linking polymerization and carbonization process. The obtained CHL-CDs exhibit bright photoluminescence centered at 671 nm, ultra-high color purity with an FWHM of 23 nm, and a high photoluminescence quantum yield of up to 62%. More importantly, based on in-depth experimental and theoretical studies on the macroscopic host–guest interactions and microscopic interfacial interactions between the CHL-CDs and charge transporting materials, high-performance red electroluminescent light-emitting diodes are successfully prepared, with FWHM of only 28 nm, turn-on voltage of 3.7 V, maximum luminance of 623 cd m−2, and maximum current efficiency of 0.26 cd A−1. This study provides a universal platform for fabricating narrow-bandwidth-emission CDs with significant applications in photoelectric devices. [ABSTRACT FROM AUTHOR]

We summarize the fabrication strategies of metallic meshes (MMs) with hard or soft templates, which produce regular-patterned or random-patterned meshes, emphasizing large scale production technology free of templates would promote the advancement of MMs. Mechanisms and strategies are highlighted in terms of enhancement in optoelectronic properties, thermal, chemical, and mechanical stability that are crucial for improving environment adaptivity of MMs. [Display omitted] Metallic meshes (MMs) are promising for replacement of traditional brittle metal oxide conductors to serve as flexible transparent devices for applications such as environment, energy, display, and human–machine-environment interface. The diversities of MMs in materials, fabrication mechanisms, geometrics and performances extend their applications, however the systematization of this field is rarely concerned. Here, this article summarizes fabrication strategies of MMs in terms of using hard or soft templates, which produce regular-patterned meshes or random-patterned meshes, emphasizing large scale production technology free of templates would lead the development of MMs. Secondly, mechanisms and strategies are highlighted in terms of enhancement of MMs in optoelectronic properties, thermal, chemical, and mechanical stability that are crucial for adapting different application scenarios. Accordingly, the representative applications of MMs in filters, shielding materials, nanogenerators, supercapacitors, solar cells, light-emitting devices, electroluminescent devices, smart windows, thermal management equipment, sensors, and touch panels are introduced, reflecting their respective advantages in diverse applications. Finally, promising solutions to balance the optoelectronic properties and the stability and durability of MMs are proposed to adapt to complex and extreme applications. It is convinced that this review can provide a comprehensive understanding to guide and promote the future development of flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

Here, we strategically propose an efficient asymmetric structure design strategy aimed at simultaneously optimizing the horizontal emitting dipole orientation and aggregation state properties of the deep-blue multi-resonance emitters. The corresponding electroluminescent device exhibited leading performance for deep-blue OLEDs, with a CIEy coordinate of 0.08, an external quantum efficiency up to 41.5%, and an excited state energy down to 2.68 eV. [Display omitted] Narrowband emitters offer significant advantages in the fabrication of next-generation deep-blue organic light-emitting diodes (OLEDs) due to their wide color gamut, high stability, and high efficiency. It is a pressing challenge to increase the light outcoupling efficiency to further boost device performance, even though 100% internal quantum efficiency is already achievable through rational molecular design. Here, we strategically propose a novel asymmetric structure design strategy aimed at simultaneously optimizing the horizontal emitting dipole orientation and aggregation state properties of the deep-blue multi-resonance (MR) emitters. This proof-of-concept emitter A-BN is capable of displaying ultrapure deep-blue emission with a peak of ∼461 nm, a small full-width-at-half-maximum of ∼25 nm, a CIEy coordinate of ∼0.08, a high horizontal dipole ratio of ∼90 %, and a near-unity photoluminescence quantum yield of ∼98 % in the practical mass-production concentration range (1–3 wt%). The corresponding non-sensitized device achieves a maximum external quantum efficiency of 41.5% without any external light extraction techniques, representing state-of-the-art performance for deep-blue OLEDs. These findings will help drive the development of highly efficient and stable narrowband deep-blue emitters and lead to a revolution in OLED technology. [ABSTRACT FROM AUTHOR]