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We report high-level calculations of the excited states of [2,2]-paracyclophane (PCP), which was recently investigated experimentally by ultrafast pump–probe experiments on oriented single crystals [Haggag et al., ChemPhotoChem 6 e202200181 (2022)]. PCP, in which the orientation of the two benzene rings and their range of motion are constrained, serves as a model for studying benzene excimer formation. The character of the excimer state and the state responsible for the brightest transition are similar to those of the benzene dimer. The constrained structure of PCP allows one to focus on the most important degree of freedom, the inter-ring distance. The calculations explain the main features of the transient absorption spectral evolution. This brightest transition of the excimer is polarized along the inter-fragment axis. The absorption of the light polarized in the plane of the rings reveals the presence of other absorbing states of Rydberg character, with much weaker intensities. We also report new transient absorption data obtained by a broadband 8 fs pump, which time-resolve strong modulations of the excimer absorption. The combination of theory and experiment provides a detailed picture of the evolution of the electronic structure of the PCP excimer in the course of a single molecular vibration. [ABSTRACT FROM AUTHOR]

Molecular emitters that combined thermally activated delayed and circularly polarized fluorescence (CP‐TADF) is of paramount importance for the next generation of displays. While most efforts have thus far focused on covalent donor and acceptor CP‐TADF emitters, a novel strategy based on chiral exciplexes has recently emerged. In this context, we present the synthesis and chiroptical properties of four new CP‐TADF exciplexes, involving two distinct C2‐symmetric bicarbazole systems and two terpyridine‐based derivatives, which serve as the chiral donor and achiral acceptor units, respectively. These exciplexes exhibit CP‐luminescence, with intensity dependent on both the chiral donor and achiral constituents, resulting in emission dissymmetry factors reaching up to 10⁻2 in the thin‐film solid state. Additionally, small singlet‐triplet gaps (∆EST ≤ 0.1 eV) have been measured, leading to TADF characteristics with a photoluminescence quantum yield of 20% for the most efficient emitter, which is also successfully used in non‐optimized organic lightemitting diodes (OLEDs). Interestingly, these chiral exciplexes allow us to explore the impact of the locally‐excited (LE) state of the chiral donor on overall exciplex emission, particularly in relation to the intensity of polarized emission—potentially highlighting a key factor in the design of this type of bimolecular CP‐TADF emitter. [ABSTRACT FROM AUTHOR]

Electron donor and acceptor interactions are the fundamentals for the emergence of optoelectronic functions in most organic devices. In particular, exciplexes, which hold the possibility to utilize dark triplets, are widely investigated in organic light‐emitting diodes. However, the relatively low radiative decay rate with a low photoluminescence quantum yield poses further advanced challenges. Traditionally, it is well recognized that exciplexes are formed through a charge transfer process, i.e., direct electron transfer, by photoexciting either a donor or an acceptor component. In this study, the focus is on a long‐range exciplex system where tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA) and 2,4,6‐tris[3‐(diphenylphosphinyl)phenyl]−1,3,5‐triazine (PO‐T2T) serve as the donor and acceptor, respectively. Moreover, 1,2‐bis(triphenylsilyl) benzene (UGH2) and bis[2‐(diphenylphosphino)phenyl]ether oxide (DPEPO), having a wide energy gap and a high triplet energy level, are employed as the double insulating layer to suppressing direct electron transfer between the donor and acceptor. The indirect through‐space exciplex formation is demonstrated by the simultaneous excitation of both donor and acceptor layers optically and electrically, providing a new route for exciplex formation. [ABSTRACT FROM AUTHOR]

Luminescent polymer composites based on polystyrene and polycarbonate doped with boron difluoride curcuminoids containing various substituents in the phenyl ring have been synthesized. The effect of substituents, polymer matrix, and luminophore concentration on the spectral properties of the polymer composites has been studied. It has been found that the effect of the electron-donating force of luminophore substituents on the emission characteristics of the films is similar to the effect of solutions. The films doped with luminophores containing alkyl substituents (1a–5a) do not change their emission characteristics upon switching to another polymer matrix, while the 6a-doped composites are characterized by positive solvatochromism. A bathofluoric shift of luminescence with an increase in the luminophore concentration to 0.5% is observed for all the films. It has been found that the 6a-doped films exhibit delayed fluorescence. [ABSTRACT FROM AUTHOR]

Organic light‐emitting diodes (OLEDs) based on multiple resonance‐thermally activated delayed fluorescence (MR‐TADF) have the advantages of high exciton utilization and excellent color purity. However, the large conjugated planarity of general MR‐TADF emitters makes them easily aggregate in the form of π–π stacking, resulting in aggregation‐caused quenching (ACQ) and the formation of excimers, which reduce exciton utilization efficiency and color purity. To address these issues, large shielding units can be incorporated to prevent interchromophore interactions, whereas the majority of reported molecules are limited to blue‐green light emissions. This work proposes a strategy of incorporating steric hindrance groups at different sites of the B/N core to suppress interactions between chromophore, contributing to blue MR‐TADF emitters with high photo‐luminance quantum yields (PLQYs ≥ 95%) and narrow full width at half maximum (FWHM), and importantly, great suppression of the ACQ effect. Therefore, blue OLEDs achieve high external quantum efficiencies up to 34.3% and high color purity with FWHM of about 27 nm and CIE around (0.12, 0.15), even at a high doping concentration of 20 wt%. [ABSTRACT FROM AUTHOR]

Here we report the synthesis and luminescent properties of the modified polyhedral oligomeric silsesquioxane (POSS) that possesses two types of luminophores, cyanobenzene and N,N‐diethylaniline for inducing significant emission not only from each dye but also from molecular interactions on the POSS core. From the optical measurements in the diluted solution, we observed both locally‐excited emission and excimer emission originating from intramolecular interactions assisted by POSS. Moreover, highly‐efficient exciplex emission was observed from the thin film, indicating that the interaction between luminophores easily occurs in the solid state by accumulating two kinds of molecules in the single POSS molecule. Finally, we also found that the modified POSS showed a unique acid responsiveness which can be caused by protonation at two types of amino moieties. In this manuscript, it is shown that POSS is able to play various roles at the same time: recruiting excited molecules to form exciplexes, suppressing concentration quenching in the solid state, and imparting stimulus responsiveness to exciplexes. [ABSTRACT FROM AUTHOR]

A new amphiphilic boron-dipyrromethene (BODIPY) dye bearing a hydrophobic 2,3,4-tris(n-dodecyloxy) phenyl group at the meso-position and two hydrophilic cationic moieties at the boron was synthesized. This dye exhibited kinetically controlled and thermodynamically controlled aggregation pathways in aqueous solution, leading to the formation of two types of J-aggregates, i.e., the metastable Agg. I and thermodynamically more stable Agg. II. Further kinetic analysis of the spontaneous transformation from Agg. I to Agg. II indicated that Agg. I was an off-pathway aggregate species. Moreover, both Agg. I and Agg. II displayed J-aggregate characteristics with enhanced fluorescence quantum yields and shortened fluorescence lifetime with respect to that of the monomeric dye. In particular, Agg. II exhibited a narrowed and intense J-band, reflecting the strong excitonic coherence in the aggregate. Morphological studies revealed that Agg. I consisted of spherical nanoparticles, while Agg. II had a multilamellar vesicular structure. In addition, in the fluorescence spectra of Agg. I and Agg. II, an unexpected broad band at longer wavelength than that of the J-aggregate emission was observed, which could be ascribed to the possible formation of excimers in these J-aggregates in aqueous solution. [ABSTRACT FROM AUTHOR]

Many stimuli‐responsive materials harness the reversible association of supramolecular binding motifs to enable advanced functionalities such as self‐healing, switchable adhesion, or mechanical adaptation. Despite extensive research into the structure–property relationships of these materials, direct correlations between molecular‐level changes in supramolecular binding and macroscopic material behaviors have mostly remained elusive. Here, we show that this challenge can be overcome with supramolecular binding motifs featuring integrated binding indicators. We demonstrate this using a novel motif that combines a hydrogen‐bonding ureido‐4‐pyrimidinone (UPy) with two strategically placed pyrene fluorophores. Dimerization of this motif promotes pyrene excimer formation, facilitating the straightforward optical quantification of supramolecular assembly under various conditions. We exploit the new motif as a supramolecular cross‐linker in poly(methyl acrylate)s to probe the extent of (dis)assembly as a function of cross‐linker content, processing history, and applied stimuli. We demonstrate that the stimuli‐induced dissociation of hydrogen‐bonding linkages strongly depends on the initial cross‐link density, which also dictates whether the force‐induced dissociation in polymer films correlates with the applied stress or strain. Thus, beyond introducing a robust tool for the in situ study of dynamic (dis)assembly mechanisms in supramolecular systems, our findings provide new insights into the mechanoresponsive behavior of such materials. [ABSTRACT FROM AUTHOR]

Mn2+-doped β-Zn2SiO4, a metastable phase of zinc silicate, is widely acknowledged for the uncertainties linked to its crystal structure and challenging synthesis process along with its distinctive yellowish luminescence. In this study, a vivid yellow luminescence originating from Mn2+-doped metastable zinc silicate (BZSM) nanophosphor is suggested, achieved through a straightforward single-step annealing process. The reliable production of this phosphor necessitates substantial doping, surplus SiO2, a brief annealing duration, and prompt cooling. The verification of the phase is demonstrated based on its optical and crystallographic characteristics. Moreover, the effective utilization of excimer lamps in practical scenarios is effectively demonstrated as a result of the vacuum ultraviolet excitation property of BZSM nanophosphor. This outcome paves the way for additional deployment of metastable zinc silicate in various fields, consequently generating novel prospects for future advancements. [ABSTRACT FROM AUTHOR]

Organic Light-Emitting Diodes (OLEDs) require several organic layers, including carrier injection layers, charge transport layers, and light-emitting layers (EML). Recently, many panel companies have been using layers with a dual function of charge transport and blocking to simplify the layer structure. At the same time, efficient charge injection into the EML is required to improve the device characteristics. In particular, the hole injection properties are important in devices using phosphorescent emitters because it is a major factor in forming the broad recombination zone. This study reports the factors influencing the device performances using three OLEDs with different electron-blocking layers (EBL). By adjusting the EBL's energy levels, it is possible to form a broad recombination zone and reduce hole accumulation and polaron-induced stress at the interface. In addition, the wide dispersion of exciton formation reduces the overcrowding of exciton which induces exciton quenching and relieves an efficiency roll-off at high luminance. Consequently, the external quantum efficiency of N-([1,1'-biphenyl]-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-11,11-dimethyl-11H-benzo[b]fluoren-3-amine with a relatively deep HOMO level is increased by more than 2% with a relaxed roll-off of 7% at 3000 cd/m2 and a device lifetime is increased fivefold compared to those of N-([1,1′-biphenyl]-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-11,11-dimethyl-11H-benzo[b]fluoren-2-amine with a relatively shallow HOMO level. [ABSTRACT FROM AUTHOR]

Exciplexes are excited-state complexes formed as a result of partial charge transfer from the donor to the acceptor species when one moiety of the donor–acceptor pair is electronically excited. The arene–amine exciplex formed between oligo-(p-phenylene) (OPP) and triethylamine (TEA) is of interest in the catalytic photoreduction of CO2 because it can compete with complete electron transfer to the OPP catalyst. Therefore, formation of the exciplex can hinder the generation of a radical anion OPP·− necessary for subsequent CO2 reduction. We report an implementation of a workflow automating quantum-chemistry calculations that generate and characterize an ensemble of structures to represent this exciplex state. We use FireWorks, Pymatgen, and Custodian Python packages for high-throughput ensemble generation. The workflow includes time-dependent density functional theory optimization, verification of excited-state minima, and exciplex characterization with natural transition orbitals, exciton analysis, excited-state Mulliken charges, and energy decomposition analysis. Fluorescence spectra computed for these ensembles using Boltzmann-weighted contributions of each structure agree better with experiment than our previous calculations based on a single representative exciplex structure [Kron et al., J. Phys. Chem. A 126, 2319–2329 (2022)]. The ensemble description of the exciplex state also reproduces an experimentally observed red shift of the emission spectrum of [OPP-4–TEA]* relative to [OPP-3–TEA]*. The workflow developed here streamlines otherwise labor-intensive calculations that would require significant user involvement and intervention. [ABSTRACT FROM AUTHOR]

The development of deep‐blue organic light‐emitting diodes (OLEDs) featuring high efficiency and narrowband emission is of great importance for ultrahigh‐definition displays with wide color gamut. Herein, based on the nitrogen‐embedding strategy for modifying the short range charge transfer excited state energies of multi‐resonance (MR) thermally activated delayed fluorescence (TADF) emitters, we introduce one or two nitrogen atoms into the central benzene ring of a versatile boron‐embedded 1,3‐bis(carbazol‐9‐yl)benzene skeleton. This approach resulted in the stabilization of the highest occupied molecular orbital energy levels and the formation of intramolecular hydrogen bonds, and thus systematic hypsochromic shifts and narrowing spectra. In toluene solution, two heterocyclic‐based MR‐TADF molecules, Py‐BN and Pm‐BN, exhibit deep‐blue emissions with high photoluminescence quantum yields of 93 % and 94 %, and narrow full width at half maximum of 14 and 13 nm, respectively. A deep‐blue hyperfluorescent OLED based on Py‐BN exhibited a maximum external quantum efficiency of 27.7 % and desired color purity with Commission Internationale de L'Eclairage (CIE) coordinates of (0.150, 0.052). These results demonstrate the significant potential for the development of deep blue narrowband MR‐TADF emitters. [ABSTRACT FROM AUTHOR]

Narrowband organic photodetectors (OPDs) conventionally necessitate high applied biases to accommodate a sufficiently thick active layer for self‐filtering functions. Herein, a concept leveraging the photomultiplication (PM) process is proposed to achieve spectral narrowing in OPDs which can operate at low external biases. This PM narrowing mechanism integrates two distinct functions through a pseudo bilayer structure comprising a photon‐filtering (PF) layer and a PM layer, respectively. The initial PF layer absorbs short‐wavelength photons and selectively permits light within a narrow bandwidth at the band edge of the PF material to enter the subsequent PM layer, thereby initiating the PM effect. The combined action of these two layers synergistically empowers the OPDs to exhibit a pronounced PM effect, resulting in a notably high external quantum efficiency of 5840% at a narrowband peak of 680 nm under a low bias of −5.0 V. Furthermore, the OPDs achieve a substantial −3 dB bandwidth of 5.2 kHz, alongside a maximum detectivity of 2.60 × 1013 Jones. These findings position the OPDs among the top‐performing self‐filtering narrowband detectors, particularly for those capable of functioning at low external biases. [ABSTRACT FROM AUTHOR]

The development of polymer‐based luminescent materials with efficient photoactivated ultralong organic phosphorescence (UOP) is of great importance but very challenging. Herein, a new class of organic phosphorescent luminogens is constructed by attaching phenyl rings and/or ethyl benzoates to the nitrogen atoms of a planar aromatic heterocycle pyrrolodiindole (PDI). The compounds show a significant elevation in phosphorescence emission capability after incorporating the ester group(s). However, they cannot produce room‐temperature phosphorescence in the crystalline state. These observations are identified to be associated with the formation of dimers and excimers and the motions of substituents within the molecules. In this context, the PDI derivatives are doped into epoxy polymers with compact and permanent 3D covalent networks. The resulting polymer films show reversible photoactivated UOP under ambient conditions, with quantum yields and lifetimes of up to 24.4% and 2.03 s, respectively, thereby enabling high‐quality and erasable light printing and multi‐level anti‐counterfeiting applications. In addition, they also exhibit excellent water and chemical resistance. This work is conducive to understanding the generation and decay mechanisms of the triplet excitons of organic luminophores with planar aromatic heterocycles in the crystalline state and provides a direction for the development of high‐performance photoactivated UOP materials. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbI3 perovskite semiconductor is attractive for deep‐red light‐emitting diodes (LEDs) because of its high photoluminescence, good thermal stability, excellent charge transport, and solution processability. However, the metastable phase of optically active CsPbI3 hinders the fabrication of efficient and bright deep‐red LEDs. Herein, a multifunctional ionic ligand regulation strategy using (2‐hydroxy‐5‐methylphenyl) triphenyl‐phosphonium iodide and 3‐(N, N‐dimethyloctylammonio) propanesulfonate is reported to regulate the optically active CsPbI3 crystallization and thus obtain high‐quality γ‐CsPbI3 thin films. The high crystallinity and preferential orientation of γ‐CsPbI3 arise from the strong bonding between the ionic ligands and ionic lead halide clusters. The obtained γ‐CsPbI3 thin films also possess suppressed defect densities, high luminescence, and high stability. Using this high‐quality thin film, an efficient and bright deep‐red LED with a peak external quantum efficiency of 13.34% and a maximum luminance of 2110 cd m−2 is successfully fabricated. The operational lifetime of the fabricated LED (time to half of the initial brightness, T50) reaches up to 40 min under a high current density of 50 mA cm−2 (corresponding to the initial brightness of 200 cd m−2). [ABSTRACT FROM AUTHOR]

Time‐dependent double hybrids with spin‐component or spin‐opposite scaling to their second‐order perturbative correlation correction have demonstrated competitive robustness in the computation of electronic excitation energies. Some of the most robust are those recently published by our group (M. Casanova‐Páez, L. Goerigk, J. Chem. Theory Comput.2021, 20, 5165). So far, the implementation of these functionals has not allowed correctly calculating their ground‐state total energies. Herein, we define their correct spin‐scaled ground‐state energy expressions which enables us to test our methods on the noncovalent excited‐state interaction energies of four aromatic excimers. A range of 22 double hybrids with and without spin scaling are compared to the reasonably accurate wavefunction reference from our previous work (A. C. Hancock, L. Goerigk, RSC Adv.2023, 13, 35964). The impact of spin scaling is highly dependent on the underlying functional expression, however, the smallest overall errors belong to spin‐scaled functionals with range separation: SCS‐ and SOS‐ωPBEPP86, and SCS‐RSX‐QIDH. We additionally determine parameters for DFT‐D3(BJ)/D4 ground‐state dispersion corrections of these functionals, which reduce errors in most cases. We highlight the necessity of dispersion corrections for even the most robust TD‐DFT methods but also point out that ground‐state based corrections are insufficient to completely capture dispersion effects for excited‐state interaction energies. [ABSTRACT FROM AUTHOR]

We found that the interfacially confined self-assembly of pyrene and phenanthrene glutamides can form strong exciplexes and amorphous superhelices, which show intensity-enhanced and sign-inverted CPL activity with improved quantum yield compared to a pyrene excimer. This work unveils the predominant role of supramolecular nanostructures over molecular configurations on CPL performance. [ABSTRACT FROM AUTHOR]

Polybenzoxazines are a class of luminescent polymers that exhibit light emission properties, making them suitable for various applications. This manuscript presents the synthesis, characterization, and thermal behavior of a novel luminescent polybenzoxazine, named P‐BZ‐CP. The synthesis of P‐BZ‐CP involved a three‐stage process, starting with the formation of Bis‐OHOMe through the reaction of cyclopentanone and vanillin, followed by a Mannich condensation reaction with p‐toluidine to obtain the monomer M‐BZ‐CP. Thermal ring‐opening polymerization of M‐BZ‐CP at 250°C resulted in the synthesis of P‐BZ‐CP. Comprehensive characterization techniques, including NMR, FTIR, XRD, SEM, TGA, and DSC, were employed to analyze the structure and properties of both M‐BZ‐CP and P‐BZ‐CP. The thermal behavior of M‐BZ‐CP curing was investigated using DSC, highlighting the temperature‐dependent polymerization process. This work also provides insights into the photophysical properties of Bis‐OHOMe, M‐BZ‐CP, and P‐BZ‐CP, highlighting the role of molecular structure and concentration in determining absorption, excitation, and emission characteristics. The core benzylidene cyclopentanone chromophore contributes to the common absorption and emission features, while the additional functional groups in M‐BZ‐CP lead to concentration‐dependent photoluminescence behavior due to aggregation or excimer formation. These findings demonstrate the importance of understanding the structure–property relationships in designing optoelectronic materials with tunable photophysical properties. The findings demonstrate the successful synthesis and characterization of luminescent polybenzoxazines, providing valuable insights into their potential applications in optoelectronics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Duration‐tunable afterglow materials have garnered considerable attention in various applications. Herein, carbon dots (CDs)‐based long persistent luminescence (LPL) composites with a tunable duration in an ultrawide range of seconds‐to‐hours levels were designed and prepared for the first time. In contrast to the established CD‐based afterglow materials, we reported that CD‐based composites exhibit LPL in the form of exciplexes and long‐lived charge‐separated states, enabling the LPL to be prolonged from several seconds to over one hour, exceeding the typical regulation range (limited to 1 min). Further studies revealed that the relationship between the excited and charge‐transfer states of CDs plays a pivotal role in activating the LPL and regulating its duration. Furthermore, these composites exhibited high photoluminescence (PL) quantum yields of up to 60.63%, and their LPL was robust under ambient conditions, even in aqueous media. Their robust and superior LPL performance endows these composites with a strong competitive advantage in dynamic display systems, such as tags for time‐resolved data encryption and displays of the remaining time of takeaways. This study offers an approach to preparing CDs‐based LPL composites with tunable durations and may provide new insights for the development of rare‐earth‐free LPL materials. [ABSTRACT FROM AUTHOR]

o-Carborane is an icosahedral cluster containing boron and has been paid attention as a versatile platform for constructing stimuli-responsive materials with solid-state luminescence properties by suppressing aggregation-caused quenching (ACQ), which is the emission annihilation process observed in condensed states, such as concentrated solutions, solids and films. Non-specific intermolecular interactions in the condensed states resulting in ACQ are disturbed by the spherical boron cluster. More recently, it has been demonstrated from several reports that o-carborane is capable of assisting solid-state excimer emission in aryl-modified o-carboranes. Moreover, some of these materials provide unique stimuli-responsiveness. In the commodity design for solid-state luminescent materials, o-carboranes are responsible for disturbing intermolecular interactions and subsequently presenting solid-state luminescence. On the other hand, excimer emission, which is inducible from the intermolecular photophysical process, has been discovered in the solid state based on o-carborane materials. In this manuscript, recent progress in stimuli-responsive luminescent materials via excimer formation will be described. Moreover, as the further potential of o-carborane materials, recent findings on the photo-salient effect which can be induced through excimer formation followed by photoreaction will also be explained. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (PQDs) have shown great promise for use in photovoltaic devices, due to their ability to offer advantages such as tunability of visible light and efficient light emission. This study demonstrates the successful utilization of a triazine-based PO-T2T (2,4,6-Tris[3(diphenylphosphenyl)phenyl]-1,3,5-triazine; PO-T2T) as the electron transport layer (ETL) through an all-solution process. To improve the structural and optical characterization of CsPbBr 3 and CsPbI 3 QDs, three organic solvents, namely chlorobenzene, methyl acetate, and ethyl acetate, were selected to find an effective orthogonal solvent for PO-T2T. The all-solution processed devices incorporating PO-T2T and Methyl acetate (MeOAc) demonstrated impressive external quantum efficiencies of 5.57% for CsPbBr 3 and 1.60% for CsPbI 3 QDs. Notably, these devices also achieved the highest maximum luminance among all-solution processed PQDs-LEDs, with values of 33334 cd m–2 for CsPbBr 3 and 224 cd m–2 for CsPbI 3 QDs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Duration‐tunable afterglow materials have garnered considerable attention in various applications. Herein, carbon dots (CDs)‐based long persistent luminescence (LPL) composites with a tunable duration in an ultrawide range of seconds‐to‐hours levels were designed and prepared for the first time. In contrast to the established CD‐based afterglow materials, we reported that CD‐based composites exhibit LPL in the form of exciplexes and long‐lived charge‐separated states, enabling the LPL to be prolonged from several seconds to over one hour, exceeding the typical regulation range (limited to 1 min). Further studies revealed that the relationship between the excited and charge‐transfer states of CDs plays a pivotal role in activating the LPL and regulating its duration. Furthermore, these composites exhibited high photoluminescence (PL) quantum yields of up to 60.63%, and their LPL was robust under ambient conditions, even in aqueous media. Their robust and superior LPL performance endows these composites with a strong competitive advantage in dynamic display systems, such as tags for time‐resolved data encryption and displays of the remaining time of takeaways. This study offers an approach to preparing CDs‐based LPL composites with tunable durations and may provide new insights for the development of rare‐earth‐free LPL materials. [ABSTRACT FROM AUTHOR]

Molecular scaffolds that enable the combinatorial synthesis of new supramolecular building blocks are promising targets for the construction of functional molecular systems. Here, we report a supramolecular scaffold based on boroxine that enables the formation of chiral and ordered 1D supramolecular polymers, which can be easily functionalized for circularly polarized luminescence. The boroxine monomers are quantitatively synthesized in situ, both in bulk and in solution, from boronic acid precursors and cooperatively polymerize into 1D helical aggregates stabilized by threefold hydrogen‐bonding and π–π stacking. We then demonstrate amplification of asymmetry in the co‐assembly of chiral/achiral monomers and the co‐condensation of chiral/achiral precursors in classical and in situ sergeant‐and‐soldiers experiments, respectively, showing fast boronic acid exchange reactions occurring in the system. Remarkably, co‐condensation of pyrene boronic acid with a hydrogen‐bonding chiral boronic acid results in chiral pyrene aggregation with circularly polarized excimer emission and g‐values in the order of 10−3. Yet, the electron deficiency of boron in boroxine makes them chemically addressable by nucleophiles, but also sensitive to hydrolysis. With this sensitivity in mind, we provide first insights into the prospects offered by boroxine‐based supramolecular polymers to make chemically addressable, functional, and adaptive systems. [ABSTRACT FROM AUTHOR]

Despite potential in high-resolution and low-cost displays and lighting, multi-doping structures and low concentrations (<1%) limit repeatability and stability of single-emissive-layer white light-emitting devices. Herein, we report a singly doped white-emitting system of blue thermally activated delayed fluorescence host matrix (CzAcSF) doped by yellow Cu4I4 cluster ([tBCzDppy]2Cu4I4). CzAcSF:x% [tBCzDppy]2Cu4I4 films realize photo- and electro-luminescence colors from cool white to warm white at x = 20–40. The external quantum efficiency of 23.5% was achieved at x = 30, indicating the record-high efficiency among solution-processed analogs and the largest doping concentration among efficient white light-emitting devices. It shows that di(tert-butyl)carbazole moieties in [tBCzDppy]2Cu4I4 provide high-lying excited energy levels at~2.6 eV to mediate energy transfer from CzAcSF (2.9 eV) to coordinated Cu4I4 (2.2 eV). Our results demonstrate the antenna effect of ligands on optimizing charge and energy transfer in organic-cluster systems and superiority of white cluster light-emitting diodes in practical applications. Multiple doping and low concentration of long-wavelength emitters suffer from repeatability and stability. Here, authors report singly-doped cluster-based white light-emitting system at high doping concentration of 30%, and optimize the charge and energy transfer based on antenna effect of ligands. [ABSTRACT FROM AUTHOR]

D2‐symmetric (R)‐binaphthyl‐bridged pyrenophanes containing thioether bonds were synthesized. The pyrenophanes exhibited the temperature‐induced sign inversion of circularly polarized luminescence (CPL) while maintaining the emission wavelength and reversibility. The Δglum value reached 0.02, and the FL quenching by heat was negligible. The sign inversion of CPL originates from the inversion of intramolecular excimer chirality associated with excitation dynamics. The two pyrenes form a kinetically trapped left‐handed twist excimer at low temperatures, while they form a thermodynamically favored right‐handed twist excimer at high temperatures. The thioether linkers can impart flexibility suitable for the inversion of chirality of the excimers. [ABSTRACT FROM AUTHOR]

Efficient inverted perovskite light‐emitting diodes (PeLEDs) are demonstrated by the introduction of tetraethyl orthosilicate (TEOS)‐incorporated tin oxide (SnO2) interlayer between the SnO2 electron injection layer and the perovskite emission layer. The TEOS incorporation into the SnO2 solution spontaneously converts it to a SiO2–SnO2 composite colloidal solution with a wide band gap, thermal stability, transparency, and chemical stability toward perovskite. The TEOS‐incorporated SnO2 interlayer effectively restricts the charge transfer from perovskite into SnO2 and promotes electron injection from SnO2 into perovskite due to the shift toward favorable energy band alignment. In addition, the TEOS‐treated interlayer balances the electron injection rate and the hole injection rate, thereby facilitating radiative recombination of the charge carriers injected into perovskite. As a result, the inverted PeLEDs exhibit significantly improved performance of 33 996 cd m−2 luminance, 9.99% of external quantum efficiency, and 44.83 cd A−1 of current efficiency. [ABSTRACT FROM AUTHOR]

Purely organic emitters that can efficiently utilize triplet excitons are highly desired for organic light‐emitting diodes (OLEDs). Hot exciton channel has emerged as a competitive strategy for the efficient harvest of triplet exciton to improve the OLEDs performance and suppress efficiency roll‐off in devices. Here, two deep blue emitters, OPACN and SPACN are designed and synthesized, employing diphenylanthracene (PAnP) unit as central core, sp3 hybridized O and S atom as conjugation blocker, and electron‐withdrawing cyano group as intramolecular charge transfer (ICT) introducer. Especially, OPACN presents bluer emission with electroluminescence (EL) peak at 436 nm, CIE coordinates of (0.16, 0.10), and a maximum external quantum efficiency (EQE) of 8.7%, while SPACN shows an EL peak at 444 nm, CIE coordinates of (0.17, 0.12) and a maximum EQE of 9.0%. Furthermore, the single‐component white organic light‐emitting diode (WOLED) based on OPACN exhibits dual emission from monomer and excimer with EQE of 5.4%. And even the luminance increases to 1000–10 000 cd m−2, the EQE still remains as high as 5.2% and 4.4%, respectively, showing very low efficiency roll‐offs. These results demonstrate an alternative approach for designing high‐performance deep blue OLEDs and WOLEDs based on single component. [ABSTRACT FROM AUTHOR]

A carbazole‐based hole‐transport‐type (p‐type) host, BPhCz, is developed using a nonsymmetrical connection strategy between two identical groups. Two benzimidazole–triazine‐based electron acceptor materials with superior electron transport abilities, namely SFX‐PIM‐TRZ and DSFX‐PIM‐TRZ, are designed to fabricate exciplex‐host systems combined with BPhCz. Exciplexes exhibit excellent carrier transport characteristics and appropriate energy levels and can serve as hosts for green multiple resonance‐induced thermally activated delayed fluorescence (MR‐TADF) devices. Efficient green MR‐TADF organic light‐emitting diodes with high color purity and low efficiency roll‐offs are successfully fabricated using the exciplexes prepared from BPhCz:SFX‐PIM‐TRZ and BPhCz:DSFX‐PIM‐TRZ as hosts, which show low driving voltages of 2.6 and 2.7 V, high maximum external quantum efficiencies (EQEs) of 35.7% and 35.5%, ultrapure green emission with Commission Internationale de L'Eclairage coordinates of (0.27, 0.69) and (0.28, 0.69), and high EQEs of 31% and 30.5% at 1000 cd m−2, respectively. [ABSTRACT FROM AUTHOR]

Developing new host materials is crucial to enhance the performance of blue organic light‐emitting diodes (OLEDs), but achieving long operational lifetimes for OLEDs has been challenging. In this study, boron‐ and silane‐based electron transport–type (n‐type) host materials, 5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yltriphenylsilane (BO‐pSi) and 2,12‐bis(triphenylsilyl)‐5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracene (BO‐2mSi), derived from boron‐ and oxygen‐based 5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracene (DOBNA) are developed. The DOBNA derivatives are modified with a triphenylsilyl blocking group to alleviate intermolecular interactions arising from the planar structure of DOBNA. The DOBNA derivatives maintain high triplet energy even in the solid state and show thermally activated delayed fluorescence features with electron transport properties. BO‐pSi is used as an n‐type host and exhibits a long operational lifetime of ≈5000 h up to 50% of the initial luminance of blue phosphorescent OLEDs. Furthermore, BO‐2mSi demonstrates a high external quantum efficiency of 7.1%, a small full width at half maximum of 33 nm, and a pure‐violet color coordinate of (0.16, 0.02) while maintaining color purity even at high doping concentrations up to 50 wt%. [ABSTRACT FROM AUTHOR]

Three new heteroleptic Ag(I) complexes, labeled as [AgL(POP)]BF4 (1–3), were successfully synthesized and comprehensively characterized. Here, L represents 2,9-bis((E)-4-methoxystyryl)-1,10-phenanthroline (L1), 2,9-bis((E)-4-methylthiostyryl) -1,10-phenanthroline (L2), and 2,9-bis((E)-4-diethylaminostyryl)-1,10-phenanthroline (L3), while POP stands for Bis[(2-diphenylphosphino)phenyl] ether. The stability of these compounds in solution was confirmed through multinuclear 1D (1H, 13C, 31P) and 2D NMR (COSY, NOESY, HMBC, HSQC) spectroscopies. Additionally, their molecular structure was elucidated via X-ray crystallography. The photophysical properties of the complexes were assessed both in the solid state and in solution (dichloromethane). Compounds 1–3 demonstrated moderate emissions in solution, with quantum yields ranging from 11–23%. Interestingly, their solid-state luminescent behavior differed. Large bathochromic shifts (42–75 nm) of the emission maxima and a decrease in quantum yields (2.5–9.5%) were evident, possibly due to the presence of excimers. Compound 3 stands out as a rare example of an Ag(I) red-color emitter. [ABSTRACT FROM AUTHOR]

Background: In previous studies, the 308‐nm light‐emitting diode (LED) has been proven safe and effective for treating vitiligo. However, direct comparisons between the 308‐nm LED and 308‐nm excimer lamp (308‐nm MEL) for the treatment of vitiligo are lacking. Objective: To compare the efficacy of the 308‐nm LED and 308‐nm MEL for treating nonsegmental stable vitiligo. Patients and Methods: This randomized controlled trial was conducted between January 2018 and August 2023. Enrolled patients were randomly assigned to either the 308‐nm LED or the 308‐nm MEL groups, both receiving 16 treatment sessions. Adverse events that occurred during the treatment were documented. Results: In total, 269 stable vitiligo patches from 174 patients completed the study. A total of 131 lesions were included in the 308‐nm LED group, and 138 lesions were included in the 308‐nm MEL group. After 16 treatment sessions, 38.17% of the vitiligo patches in the 308‐nm LED group achieved repigmentation of at least 50% versus 38.41% in the 308‐nm MEL group. The two devices exhibited similar results in terms of efficacy for a repigmentation of at least 50% (p =.968). The incidence of adverse effects with the two phototherapy devices was comparable (p =.522). Conclusions: Treatment of vitiligo with the 308‐nm LED had a similar efficacy rate to the 308‐nm MEL, and the incidence of adverse effects was comparable between the two devices. [ABSTRACT FROM AUTHOR]

DNA‐based hybrid materials have attracted much attention recently for their biocompatibility, tunable optical, and semiconducting properties. In this study, thin films fabricated using native DNA are modified to accommodate the assembled fluorescent dyes (perylene and 3‐bromoperylene), alongside the systematical evaluation of their photophysical properties and performance. Spectroscopy results reveal successful modulation of the molecular excitonic behaviour, achieve switchable single‐chromophore multi‐color emission in DNA‐surfactant‐dye thin films, with high optical transparency and thermal robustness. The nucleotide base pairs effectively suppress unfavorable intermolecular π–π stacking and aggregation (self‐association) of the chromophores, which prevents intersystem crossing and relaxation associated Rydberg type molecular clusters to form intermolecular excimers in E‐state (532, 513 nm) and Y‐state (489, 483 nm), blocking nonradiative decay. The preeminent emission observed (457, 445 nm) is attributed to the 0–1 band monomer emission. Compared to PMMA‐dye assembly, the thin film derived from DNA‐surfactant‐dye hybrid narrows the FWHM values up to 72%, displayed molarity ratio‐dependent emission color tunability from yellow‐orange (CIE 0.47, 0.34) to green (CIE 0.31, 0.21) and blue (CIE 0.17, 0.23). These findings provide a simple, all‐solution processed strategy for creating thin films using DNA‐surfactant‐dye hybrid materials with tunable optical properties suitable for biocompatible displays and data encryption. [ABSTRACT FROM AUTHOR]

Single‐molecule white‐light and near‐infrared circularly polarized luminescent materials are effective complements to the demonstrated enhancements of visible emission in the high contrast 3D images or organic light‐emitting diodes. In this contribution, two binaphthalene‐containing luminogenic enantiomers (BIT or BITM) with aggregation‐induced emission are synthesized which exhibit circularly polarized luminescence in solution with dissymmetry factors of ±5.0 × 10−3 and ±4.8 × 10−3, respectively. Additionally, the dual‐fluorescence spectra of single‐molecule white emission (CIE: 0.33, 0.34) in toluene solution are observed with (R)/(S)‐BIT in low polarity solvent originating from locally excited and twisted intramolecular charge‐transfer emission. While (R)/(S)‐BITM only shows single NIR luminescence with peaks at 720 nm in powder state. The nondoped OLEDs exhibit high maximum external quantum efficiencies of up to 4.2% with small efficiency roll‐off and NIR electroluminescence peak at 709 nm. [ABSTRACT FROM AUTHOR]

Tunable emission wavelength and excellent biocompatibility have positioned silicon quantum dots (Si QDs) as important optoelectronic materials in areas like displays, lighting, and biomedical imaging. However, the challenges of low luminescence efficiency impede the utilization of Si QDs, restraining the advancement of Si QDs‐based light‐emitting diode (LED) devices. This study primarily concentrates on optimizing the surface structure of Si QDs and refining the Si QDs‐based LED device structures. A strategy involving active oxidation followed by hydrofluoric etching and hydrosilylation is proposed to enhance the optical characteristics of Si QDs. A variety of characterization methods are employed to evaluate the impact of the active oxidation on the photoluminescence and surface structures of Si QDs. This approach ultimately achieves an impressive enhancement in the photoluminescence quantum yield (PL QY) of Si QDs from 6.7% to 60.3%. Furthermore, the atmospherically oxidized Si QDs with the highest PL QY are selected as the emitting‐layer material to fabricate LEDs with the structure of ITO/PEDOT:PSS/TFB/Si QDs/ZnMgO/Ag. The introduction of ZnMgO effectively balances charge injection in the Si‐QDs‐based LEDs. As a result, the devices achieve electroluminescence with an external quantum efficiency of 13.2%. [ABSTRACT FROM AUTHOR]

Scintillators are essential in converting ionizing X‐rays and γ‐rays into visible light, with applications in medical diagnosis, security inspection, and non‐invasive detection. However, current scintillating materials exhibit unclear structure–function relationships. The performance of scintillators is intricately linked to their electronic band structure, particularly the intrinsic properties of excited states. Therefore, investigating the structural factors affecting scintillation performance is crucial for developing new scintillators. Therefore, Ba‐SMOF 1 ([Ba2(PyTS)(CH3OH)2(H2O)4]n) is synthesized using a pyrene‐based organic motif and metal Ba(II) ions, where PyTS4− refers to pyrene‐1,3,6,8‐tetrasulfonate. For the first time, the excited state of a pyrene‐based X‐ray scintillating metal–organic framework (MOF) is determined through comprehensive all‐electron excitation studies, including in situ experimental electron density and wave‐function analysis. The electron density maps exhibit a continuous overlap, attributed to the associative exciton behaviors among the closely packed PyTS4− linkers. These linkers are identified as the sources of both static and dynamic excimer emissions. The electron density studies reveal the role of excimers in pyrene‐based luminophores, highlighting that interchromophoric interactions are key to enhancing the performance of scintillating MOFs. This discovery opens new avenues for the practical application of scintillating MOFs. [ABSTRACT FROM AUTHOR]

Herein, we report the unique multiple‐stimuli responsiveness of anthracene‐tethered o‐carborane derivatives. We designed and synthesized anthracene derivatives with different substitution positions and numbers of the o‐carborane units. Two compounds had characteristic crystal structures involving the columnar π‐stacking structures of the anthracene units. From the analysis of crystalline‐state structure–property relationships, it was revealed that the crystals exhibited the photosalient effect accompanied by photochemical [4+4] cycloaddition reactions and temperature‐dependent photophysical dual‐emission properties including excimer emission of anthracene. Those properties were considered as non‐radiative and radiative deactivation pathways through the excimer formation in the excited state and the formation of excimer species was facilitated by the π‐stacking structure of anthracene units. Moreover, we found unusual temperature dependency on the occurrence of the photosalient effect. According to the data from variable temperature X‐ray crystallography, a strong correlation between lattice shrinkage and strain accumulation is suggested. [ABSTRACT FROM AUTHOR]

Although sensitizing traditional fluorescent dyes with thermally activated delayed fluorescence (TADF) exciplexes has been extensively studied, the device performance of solution‐processed organic light‐emitting diodes (OLEDs) still lags far behind in this regard. Herein, the novel exciplex with high up‐conversion efficiency composed of a triazatruxene‐based donor and a triazine‐based acceptor is employed as a TADF sensitizer to fluorescent dye in solution‐processed hyperfluorescent OLEDs. Benefiting from the small activation energy for triplet up‐conversion and less non‐radiative recombination of triplet excitons, the new TADF exciplex can up‐convert efficiently non‐radiative triplet excitons through reverse intersystem crossing. Besides, expeditious up‐conversion processes also shorten the residence time of triplet excitons, giving rise to significant suppression of detrimental Dexter energy transfer from the exciplex sensitizer to the dopant. By maximizing the triplet up‐conversion efficiency of exciplex sensitizers, the optimized OLEDs achieve a maximum external quantum efficiency (EQEmax) of 16.0%, which is the first report for the solution‐processed exciplex‐sensitized hyperfluorescent OLEDs with EQEmax exceeding 15%. These results validate that the up‐conversion efficiency of triplet excitons in the exciplexes strongly affects the performance of exciplex‐sensitized fluorescent devices, and the triazatruxene‐based molecules are promising donor candidates for constructing the exciplexes with high up‐conversion efficiency. [ABSTRACT FROM AUTHOR]

Inverted organic light-emitting devices (OLEDs) have been aggressively developed because of their superiorities such as their high stability, low driving voltage, and low drop of brightness in display applications. The injection of electrons is a critical issue in inverted OLEDs because the ITO cathode has an overly high work function in injecting electrons into the emission layer from the cathode. We synthesized hexagonal wurtzite ZnO nanoparticles using different oxidizing agents for an efficient injection of electrons in the inverted OLEDs. Potassium hydroxide (KOH) and tetramethylammonium hydroxide pentahydrate (TMAH) were used as oxidizing agents for synthesizing ZnO nanoparticles. The band gap, surface defects, surface morphology, surface roughness, and electrical resistivity of the nanoparticles were investigated. The inverted devices with phosphorescent molecules were prepared using the synthesized nanoparticles. The inverted devices with ZnO nanoparticles using TMAH exhibited a lower driving voltage, lower leakage current, and higher maximum external quantum efficiency. The devices with TMAH-based ZnO nanoparticles exhibited the maximum external quantum efficiency of 19.1%. [ABSTRACT FROM AUTHOR]

The recent trend of combining perovskite with other materials to enhance optoelectronic performance has garnered significant interest. In this paper, MAPb0.9Sn0.1I3 and ZnO–MAPb0.9Sn0.1I3 photodetector were prepared by frequency magnetron sputtering and sol–gel spin-coating method. Hybrid heterojunction photodetectors have more beneficial optoelectronic performance compared to MAPb0.9Sn0.1I3 photodetector, due to the presence of built-in electric fields, which can suppress the recombination of electrons and holes. At 7 V bias conditions, the responsivities of MAPb0.9Sn0.1I3 photodetector were 0.022 and 0.015 A/W, and the responsivities of ZnO–MAPb0.9Sn0.1I3 photodetector were 0.39 and 0.99 A/W obtained under 350 and 850 nm illumination, respectively. The maximum external quantum efficiency reaches 144.47%, the detection rate was 5.53 × 1011 Jones and the light to dark ratio was 2.95 × 103 of ZnO–MAPb0.9Sn0.1I3 photodetector. This study provides a basis for the preparation of perovskite heterojunction photodetectors with high optoelectronic performance. High performance UV–vis–NIR photodetectors based on ZnO/organic–inorganic hybrid Sn–Pb hybrid perovskite heterojunction. [ABSTRACT FROM AUTHOR]

Chemical doping is a significant means to modulate bandgap structures and optoelectronic properties of transition metal dichalcogenides (TMDCs). Herein, an Er3+/Yb3+ co‐doped WS2 monolayer with ultrahigh and tunable concentrations is successfully fabricated by in‐situ chemical vapor deposition (CVD) technique. The morphologies, thicknesses, components, and structures of the samples are systemically characterized by optical microscope, atomic force microscopy, Raman, X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscope with energy dispersive spectrometer, and high‐resolution transmission electron microscopy, respectively. Photoluminescent peaks are enhanced significantly with red shifts, and the absorption is broadened to near‐infrared, implying a shrinked bandgap after RE co‐doping, which is consistent to the calculation results by density functional theory (DFT). The Er3+/Yb3+ co‐doped WS2 device demonstrates high carrier mobility, photocurrent, photoresponsivity, external quantum efficiency, and specific detectivity, which are approximately two orders of magnitudes compared with those of the pristine WS2 device. The values of photoresponsivity and specific detectivity approach 4.8 × 104 A W−1 and 5.5 × 1014 Jones, respectively, at 20 V bias and 1.77 mW cm−2 luminescence, which may refresh the records as has been reported. The excellent performances of the WS2 photodetector prove the effectiveness of Er3+/Yb3+ co‐doping for practical application in optoelectronics. [ABSTRACT FROM AUTHOR]

A new carbazole-coupled tetrakis-(1 H-pyrrole-2-carbaldehyde) anion receptor 1 has been designed and synthesized. Anion binding studies in organic media using fluorescence and UV-vis spectroscopy revealed that receptor 1 is capable of sensing HP2O73- with high selectivity. Addition of HP2O73- to THF solution of 1 resulted in the emergence of a new broad band at longer wavelength along with quenching of the original emission band forming a ratiometric response. Based on dynamic light scattering (DLS) experiment and fluorescence lifetime measurement, we propose that the emergence of new emission band in the presence of HP2O73- ion is due to the aggregation-induced excimer formation. [ABSTRACT FROM AUTHOR]

A new carbazole-coupled tetrakis-(1 H-pyrrole-2-carbaldehyde) anion receptor 1 has been designed and synthesized. Anion binding studies in organic media using fluorescence and UV-vis spectroscopy revealed that receptor 1 is capable of sensing HP2O73- with high selectivity. Addition of HP2O73- to THF solution of 1 resulted in the emergence of a new broad band at longer wavelength along with quenching of the original emission band forming a ratiometric response. Based on dynamic light scattering (DLS) experiment and fluorescence lifetime measurement, we propose that the emergence of new emission band in the presence of HP2O73- ion is due to the aggregation-induced excimer formation. [ABSTRACT FROM AUTHOR]

Singlet fission (SF), a process that produces two triplet excitons from one singlet exciton, has attracted recent interest for its potential to circumvent the detailed-balance efficiency limit of single-junction solar cells. For the potential of SF to be fully realized, accurate assignment and quantification of SF is necessary. Intersystem crossing (ISC) is another process of singlet to triplet conversion that is important to distinguish from SF to avoid either over- or under-estimation of SF triplet production. Here, we quantify an upper bound on the rate of ISC in two commonly studied SF chromophores, TIPS–pentacene and TIPS–tetracene, by using transient absorption spectroscopy of solutions of varying concentrations in toluene. We show that SF in solutions of these acenes has previously been misidentified as ISC, and vice versa. By determining a bimolecular SF rate constant in concentrated solutions in which SF dominates over ISC, we distinguish triplet formation due to SF from triplet formation due to ISC and show that the characteristic time scale of ISC must be longer than 325 ns in TIPS–pentacene, while it must be longer than 118 ns in TIPS–tetracene. We additionally note that no excimer formation is observed in the relatively dilute (up to 8 mM) solutions studied here, indicating that previous excimer formation observed at much higher concentrations may be partially due to aggregate formation. This work highlights that an accurate quantification of ISC is crucial as it leads to accurate determination of SF rate constants and yields. [ABSTRACT FROM AUTHOR]

Pyrene based molecules are inclined to form excimers through self-association upon photoexcitation. In this work, the pyrene core is functionalized with the N-methylacetamide group at the position 1 or 2 to develop pyren-1-methylacetamide (PyMA1) and pyren-2-methylacetamide (PyMA2), respectively. Upon photoexcitation with 345 nm, a portion of molecules in PyMA1 and PyMA2 solutions at ≥1.0 mM have formed static excimers. The steady state spectroscopic measurements suggest that, whether it is the dimerization of molecules in the ground state (GS) or in excimer formation, characteristic signs are more pronounced in PyMA1 than its isomeric counterpart, PyMA2. The shift of the excimer band in their respective emission spectra suggests that the extent of overlap in π–π stacking is greater for PyMA1 than for PyMA2 in the excited state. The optimized geometry of dimers in toluene shows that the overlapping area between the pyrene moieties in π–π stacking between the dimers is greater for PyMA1 than for PyMA2 in GS. The natural bond orbital analysis with the optimized GS geometries shows that the stabilization/interaction energy between the dimers in π–π stacking is higher in PyMA1 compared to PyMA2 in toluene. The transient absorption (TA) measurements in toluene over the fs–ps regime (fs-TA) showed that the formation of static excimers with pre-associated dimers in PyMA1 happens in ∼700 fs whereas the excimers for the pre-associated dimers in PyMA2 have formed in slightly slower time scale (∼1.95 ps). Contrary to what was observed in solution, the extent of overlap in π–π stacking is lower for PyMA1 dimers (∼17%) than for PyMA2 dimers (∼37%) in single crystals. [ABSTRACT FROM AUTHOR]

We reported the synthesis of a series of structurally diverse CPL‐active molecules, in which pyrene units were installed to chiral pm/po‐[2,2]PCP scaffolds either with or without a triple bond spacer for pm/po‐PCP‐P1 and pm/po‐PCP‐P2, respectively. The X‐ray crystallographic analyses revealed that these pyrene‐based [2,2]PCP derivatives exhibited diverse structures and crystal packings in the solid phases. The pyrene‐based [2,2]PCP derivatives exhibit various (chir)optical properties in organic solutions, depending on their respective structures. In a mixture of dioxane and water, pm/po‐PCP‐P1 emit green excimer fluorescence, whereas pm/po‐PCP‐P2 emit blue one. The chiroptical investigation demonstrated that Rp‐pm‐PCP‐P1 and Rp‐pm‐PCP‐P2 exhibited completely opposite CD and CPL signals even they possess the same chiral Rp‐[2,2]PCP core. The same argument also holds for other chiral pyrene‐based [2,2]PCP derivatives. The theoretical calculation revealed that these unusual phenomena were attributed to different orientation between transition electric dipole moments and the magnetic dipole moments originating from the presence or absence of a triple bond spacer. These pyrene‐based [2,2]PCP derivatives display various colours and fluorescence emissions in the solid state and PMMA films, possibly due to the different packings as observed in the crystal structure. Moreover, these compounds also can interact with perylene diimide through π‐π interactions, leading to near‐white fluorescence. [ABSTRACT FROM AUTHOR]

Aggregation‐Induced Emission (AIE) luminogens have garnered significant interest due to their distinctive applications in different applications. Among the diverse molecular architectures, those based on triphenylamine and thiophene hold prominence. However, a comprehensive understanding of the deactivation mechanism both in solution and films remains lacking. In this study, we synthesized and characterized spectroscopically two AIE luminogens: 5‐(4‐(bis(4‐methoxyphenyl)amino)phenyl)thiophene‐2‐carbaldehyde (TTY) and 5′‐(4‐(bis(4‐methoxyphenyl)amino)phenyl)‐[2,2′‐bithiophene]‐5‐carbaldehyde (TTO). Photophysical and theoretical analyses were conducted in both solution and PMMA films to understand the deactivation mechanism of TTY and TTO. In diluted solutions, the emission behavior of TTY and TTO is influenced by the solvent, and the deactivation of the excited state can occur via locally excited (LE) or twisted intramolecular charge transfer (TICT) state. In PMMA films, rotational and translational movements are constrained, necessitating emission solely from the LE state. Nevertheless, in the PMMA film, excimers‐like structures form, resulting in the emergence of a longer wavelength band and a reduction in emission intensity. The zenith of emission intensity occurs when molecules are dispersed at higher concentrations within PMMA, effectively diminishing the likelihood of excimer‐like formations. Luminescent Solar Concentrators (LSC) were fabricated to validate these findings, and the optical efficiency was studied at varying concentrations of luminogen and PMMA. [ABSTRACT FROM AUTHOR]

The deviated crystallization kinetics of solution‐processed perovskite layers caused by the bottom interface is a barrier to comprehensively suppressing the defect formation and further to efficaciously improve the film quality and device performance. Herein, it is reported that the incorporation of a PEA2PbBr4 interlayer can effectively modify the crystallization process of the quasi‐2D mixed‐halide perovskite layers, resulting in enhanced Lewis acid‐base interaction and improved film homogeneity, which contributes to the strong defect passivation efficacy toward efficient sky‐blue emission. As a result, the devices with the bottom‐interface modification show a maximum external quantum efficiency of 14.2%, impressively an outstanding power efficiency of 17.0 lm W−1, and an external quantum efficiency of 12.3% at 1000 cd m−2. This work provides an insight into crystallization kinetics for defect suppression of the perovskite layer and further highlights the defect passivation efficacy of 2D perovskite‐based bottom‐interface modification toward high‐efficiency sky blue‐emitting diodes. [ABSTRACT FROM AUTHOR]

Controlling chromophore chirality in three‐dimensional space is crucial for understanding the structure–chiroptical relationship. Such control enables the prediction of ideal materials for use in chiral photonic applications. In this study, optically active multipyrene systems are synthesized on peptoids. Pyrene‐based chiral submonomers, (S)‐ and (R)‐1‐pyrenylethylamine (s1pye and r1pye), are successfully incorporated into peptoids as the respective (S)‐ and (R)‐N‐(1‐pyrenylethyl)glycine (Ns1pye and Nr1pye) units. NMR spectroscopy revealed length‐ and N‐acetylation‐dependent conformational homogeneity enhancement in solution, stabilizing cis‐amides in Ns1pye‐containing peptoids. The X‐ray crystal structure of Ns1pye tetramer displayed a polyproline type‐I (PPI)‐like helix. All of the pyrene‐related absorptions are circular dichroism (CD) active, and the CD signal related to the long‐axis‐polarized transition increased with helical stabilization. Intramolecular excimer generation yielded significant circularly polarized luminescence (CPL) in the excimer emission region. Early‐stage peptoids emitted left‐handed CPL, but upon acquiring a PPI‐like helix character, CPL handedness became inverted. The CPL dissymmetry factor (glum) was comparable or superior (10−2) to that of chiral organic dyes (10−5–10−2). This new class of helical pyrene‐containing peptoids provides a CPL‐active intramolecular excimer, modulating optical activity through peptoid secondary structure homogeneity. [ABSTRACT FROM AUTHOR]

The spectral and photochemical properties of a biphotochromic dyad in which two 2-[2-(pyren-1-yl)ethenyl]quinoline (PEQ) photochromes are linked to each other by the bridging ortho-xylylene group have been studied. An excimer has been detected in the dyad according to a bathochromic shift of the fluorescence spectrum. Under exposure to light, the dyad undergoes photoisomerization reactions of PEQ photochromes and intramolecular [2+2]-photocycloaddition (PCA) with the formation of dipyrenyl-substituted cyclobutane. It is assumed that the tendency of PEQ photochromes to π-stacking interaction has a positive effect at the first step of the PCA reaction, promoting the formation of preorganized dimeric structures in the ground S0 state, which give an excimer in the excited S1 state, and a negative effect at the second step, preventing the movement of photochromes relative to each other, which is necessary to achieve conformations favorable to the PCA reaction. [ABSTRACT FROM AUTHOR]

The dual emission (DE) feature in materials holds great potential to revolutionize the development of one‐component system white organic light‐emitting diodes (WOLEDs). However, the reported DE materials remain scarce owing to the formidable challenge of breaking Kasha's rule and managing the intricate energy/charge transfer processes. Herein, we have introduced a groundbreaking DE AIEgen, 2CzAn‐TPE, which possesses a simple structure and undergoes Z‐to‐E isomerization and exhibits yellow and red fluorescence powders for pre‐ and post‐sublimation, respectively. With relatively lower potential energy, Z‐conformation ((Z)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) of 2CzAn‐TPE can be readily transformed into E‐conformation ((E)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) via vacuum sublimation. The utilization of X‐ray diffraction and grazing‐incidence‐wide‐angle X‐ray scattering techniques confirms the structural transformation, while the crystallographic analysis reveals the establishment of numerous intermolecular CH···π interactions between the tetraphenylethene (TPE) moiety and both the anthracene and carbazole units. This allows a densely packed molecular arrangement, thereby offering propitious conditions for excimer generation in the E‐conformation aggregated state. By utilizing the sublimated 2CzAn‐TPE as an emitter, a nondoped one‐component WOLED was prepared, exhibiting an exceptionally high external quantum efficiency (EQE) of 5.0%, which represents one of the highest performances among all one‐component WOLEDs. This research introduces a novel, simple, and efficient approach to realize highly efficient one‐molecule WOLEDs. [ABSTRACT FROM AUTHOR]