Helical molecular carbons (HMCs) possess high absorption/luminescence dissymmetry factors (gabs/glum) and significant luminescence quantum yield (Φlum), resulting in a high circularly polarized luminescence (CPL) brightness (BCPL), which is essential for the development of CPL materials for practical applications. Herein, we designed and synthesized a series of boron‐nitrogen (BN)‐doped HMCs, named π‐extended heli(aminoborane)s (E[10]HAB‐A, E[10]HAB‐B and E[10]HAB‐C), consisting of laterally π‐extended [10]helicene skeleton with alternating N and B atoms at the inner rim. The aromaticity, electronic structures, and photophysical properties of E[10]HAB‐A/B/C were systematically investigated through experiments and theoretical calculations. E[10]HAB‐A/B/C displayed remarkable photophysical properties, including high molar extinction coefficient and bright narrowband emission. The isolated enantiomers of E[10]HAB‐A/B/C exhibited intense circular dichroism (CD) and CPL, in which E[10]HAB‐A shows gabs and glum values up to 0.024 and 0.017, simultaneously with high Φlum of 82% and a narrow full width at half maximum of 16 nm. Accordingly, E[10]HAB‐A exhibits a BCPL as high as 583 M−1 cm−1, which is the largest value among the reported BN‐doped HMCs. Our study indicates that inner rim BN‐doping and π‐extension are effective strategies to achieve high Φlum and balanced glum values in HMCs.

Blue tetradentate Pt(II) emitters and the corresponding organic light-emitting diodes (OLEDs) are promising for next-generation high-resolution displays. However, developing blue Pt(II) emitters that simultaneously achieve high efficiency, high color purity, and excellent operational stability remains challenging. In this study, we developed two new high-performance deep blue tetradentate Pt(II) emitters (Pt1 and Pt2) whose ligands contain 1-(3,5-di-tert-butylphenyl)-9,9-dimethyl-1,9-dihydrofluoreno[2,3-d]imidazolium or 3-(3,5-di-tert-butylphenyl)-9,9-dimethyl-3,9-dihydrofluoreno[2,3-d]imidazolium carbene moiety (DMFI). These Pt(II) emitters display excellent photophysical characteristics including high photoluminescence quantum yield (PLQY) of up to 0.90, narrow full width at half maximum (FWHM), short emission lifetime, and high horizontal transition dipole ratio of up to 0.80. As a result, deep blue phosphorescent OLEDs are fabricated with a narrow FWHM of 21 nm, a high maximum external quantum efficiency (EQEmax) of 28.6%, and Commission Internationale de l'& Eacute;clairage (CIE) coordinates of (0.13, 0.15). Even more impressively, the devices based on the deuterated co-host system and different device structures achieved an unprecedented excellent device lifetime LT95 of 290 h at an initial luminance of 1000 cd m-2, an EQEmax of 20.8%, and CIE coordinates of (0.14, 0.17).

Phosphorescent metal complexes, especially Pt(II) complexes, are widely used as emissive materials in organic light-emitting diodes (OLEDs) due to their tunable emissions and ease of preparation. To enable practical OLED...

Heteroatom‐embedded helical nanographenes (NGs) constitute an important and appealing class of intrinsically chiral materials. In this work, a series of B,N‐embedded helical NGs bearing azepines was synthesized via stepwise regioselective cyclodehydrogenation. First, the phenyl‐ or nitrogen‐bridged dimers were efficiently clipped into highly congested model compounds 1 and 2. Later, the controllable Scholl reactions of the tetraphenyl‐tethered precursor generated 1, 7 or 8 new C‒C bonds, thereby establishing a robust method for the preparation of nonalternant BN‐HNGs with up to 31 fused rings. The helical bilayer nature was unambiguously verified by X‐ray diffraction analysis. The helical chirality was transferred to the stereogenic boron centers upon fluoride coordination, with a concave‐concave structure to comply with the bilayer skeleton. Notably, the largest nonalternant BN‐HNG (6) spontaneously resolved into a homochiral 41 helix structure as a molecular spiral staircase during crystallization via conglomerate formation at the single‐crystal scale. The large twisted C2‐symmetric pi‐surface and the dynamic chiral skeleton induced by curved azepines might have synergistic effects on self‐recognition of enantiomers of 6 to achieve the intriguing spontaneous resolution behavior. The chiroptical properties of the enantiomer of 6 were further investigated, revealing that 6 had a strong chiroptical response in the visible range (400–700 nm).

Pt-based green OLEDs exhibit a maximum EQE of up to 29.6% and an LT 95 of up to 17 140 hours at 1000 cd m −2 .

Atomically precise synthesis of three-dimensional boron-nitrogen (BN)-based helical structures constitutes an undeveloped field with challenges in synthetic chemistry. Herein, we synthesized and comprehensively characterized a new class of helical molecular carbons, named benzo-extended [n]heli(aminoborane)s ([n]HABs), in which the helical structures consisted of n = 8 and n = 10 ortho-condensed conjugated rings with alternating BN atoms at the inner rims. X-ray crystallographic analysis, photophysical studies, and density functional theory calculations revealed the unique characteristics of this novel [n]HAB system. Owing to the high enantiomerization energy barriers, the optical resolution of [8]HAB and [10]HAB was achieved with chiral high-performance liquid chromatography. The isolated enantiomers of [10]HAB exhibited record absorption and luminescence dissymmetry factors (|g abs|=0.061; |g lum|=0.048), and boosted CPL brightness up to 292 M-1 cm(-1), surpassing most helicene derivatives, demonstrating that the introduction of BN atoms into the inner positions of helicenes can increase both the |g abs| and |g lum| values.

AbstractThe design of high‐entropy single‐atom catalysts (HESAC) with 5.2 times higher entropy compared to single‐atom catalysts (SAC) is proposed, by using four different metals (FeCoNiRu‐HESAC) for oxygen reduction reaction (ORR). Fe active sites with intermetallic distances of 6.1 Å exhibit a low ORR overpotential of 0.44 V, which originates from weakening the adsorption of OH intermediates. Based on density functional theory (DFT) findings, the FeCoNiRu‐HESAC with a nitrogen‐doped sample were synthesized. The atomic structures are confirmed with X‐ray photoelectron spectroscopy (XPS), X‐ray absorption (XAS), and scanning transmission electron microscopy (STEM). The predicted high catalytic activity is experimentally verified, finding that FeCoNiRu‐HESAC has overpotentials of 0.41 and 0.37 V with Tafel slopes of 101 and 210 mVdec−1 at the current density of 1 mA cm−2 and the kinetic current densities of 8.2 and 5.3 mA cm−2, respectively, in acidic and alkaline electrolytes. These results are comparable with Pt/C. The FeCoNiRu‐HESAC is used for Zinc–air battery applications with an open circuit potential of 1.39 V and power density of 0.16 W cm−2. Therefore, a strategy guided by DFT is provided for the rational design of HESAC which can be replaced with high‐cost Pt catalysts toward ORR and beyond.

We provide the rational design of dual atom catalysts (DACs) supported on nitrogen-doped graphene for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through high-throughput computational screening of M(1)M(2)N6-DAC systems, where M-1 and M-2 represent Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, or Pt metals. We predict that FeRuN6-DAC at the summit of the volcano plot exhibits a low theoretical ORR overpotential (eta(ORR)) of 0.24 V and a low theoretical OER overpotential (eta(OER)) of 0.19 V. The low eta(ORR) and eta(OER) result from the catalytic performance of the Fe site being tuned to electronic properties that facilitate adsorption and desorption of the OH* intermediate. Inspired by these hybrid density functional theory (DFT) computational and machine learning (ML) results, we synthesized FeRuN6-DAC, FeN4-SAC, and RuN4-SAC and characterized them using Xray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and in-situ electron spin resonance (ESR). Our in-situ ESR spectroscopy signifies that the spin of the Fe active site increases with increasing applied potential due to the increase in the concentration of OH* intermediate on Fe. We verified experimentally the predicted catalytic performances, finding that FeRuN6-DAC leads to an experimental ORR overpotential of 0.29 V with a Tafel slope of 104 mVdec(-1) and an OER overpotential of 0.27 V with a Tafel slope of 124 mVdec(-1). The rechargeable Zinc-air battery setup was fabricated with FeRuN6-DAC in place of the cathode, showing a maximum power density of 0.45 W/cm(2) at the current density of 0.44 A/cm(2) and good stability after 120 cycles. According to our findings, we demonstrate that DFTguided strategies are useful for designing advanced DACs applicable to ORR, OER, and Zinc-air battery applications.

Due to the low-lying Pd(4d)-orbitals, luminescent palladium(II) complexes usually show 3IL phosphorescence (IL = intraligand) with excited state lifetimes in the range of hundreds of microseconds, which limits their application in blue organic light-emitting diodes (OLEDs). Here, a molecular design strategy for the development of strongly luminescent Pd(II)-based thermally activated delayed fluorescence (TADF) emitters with fast radiative decay rate constants and reverse intersystem crossing rate (kRISC) constants is presented. The synthesized tetradentate [Pd(N*C*C<^>N)] TADF emitters show sky-blue to yellow (lambda max = 484-565 nm) emission with excited state lifetimes in the range of 0.9-8.7 mu s and high photoluminescence quantum yield of up to 77% in CH2Cl2 solution. In 5 wt.% 2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan (PPF) thin films, these [Pd(N*C*C<^>N)] TADF complexes display blue to sky-blue (476-496 nm) emission with quantum yields close to unity. Variable-temperature emission lifetime measurements, femtosecond time-resolved spectroscopy, and density functional theory (DFT) and time-dependent DFT (TDDFT) calculations together reveal ultrafast kRISC rate constants of these [Pd(N*C*C<^>N)] TADF emitters. Using these Pd(II)-TADF emitters as dopants, sky-blue TADF and blue TADF-sensitized OLEDs with small efficiency roll-offs achieved high maximum external quantum efficiencies (EQEs) of 24.8% and 23.1%, respectively. Strongly luminescent tetradentate [Pd(N*C*C<^>N)] TADF emitters are developed for achieving high-performance vapour-deposited sky-blue TADF and blue TADF-sensitized OLEDs. The blue Pd-TADF-sensitized OLED displays a narrow electroluminescence spectrum with FWHM down to 24 nm, high EQE and CE of up to 23.1% and 51.7 cd A-1, respectively, alongside a low EQE roll-off down to 6% at a practical luminance of 1000 cd m-2.image

Introducing helical subunits into negatively curved π-systems has a significant effect on both the molecular geometry and photophysical properties; however, the synthesis of these helical π-systems embedded with nonbenzenoid subunits remains challenging due to the high strain deriving from both the curvature and helix. Here, we report a family of nonalternant nanographenes containing a nitrogen (N)-doped cyclopenta[ef]heptalene unit. Among them, CPH-2 and CPH-3 can be viewed as hybrids of benzoannulated cyclopenta[ef]heptalene and aza[7]helicene. The crystal structures revealed a saddle geometry for CPH-1, a saddle-helix hybrid for CPH-2, and a twist-helix hybrid for CPH-3. Experimental measurements and theoretical calculations indicate that the saddle moieties in CPHs undergo flexible conformational changes at room temperature, while the aza[7]helicene subunit exhibits a dramatically increased racemization energy barrier (78.2 kcal mol-1 for CPH-2, 143.2 kcal mol-1 for CPH-3). The combination of the nitrogen lone electron pairs of the N-doped cyclopenta[ef]heptalene unit with the twisted helix fragments results in rich photophysics with distinctive fluorescence and phosphorescence in CPH-1 and CPH-2 and the similar energy fluorescence and phosphorescence in CPH-3. Both enantiopure CPH-2 and CPH-3 display distinct circular dichroism (CD) signals in the UV-vis range. Notably, compared to the reported fully π-extended helical nanographenes, CPH-3 exhibits excellent chiroptical properties with a |gabs| value of 1.0 × 10-2 and a |glum| value of 7.0 × 10-3; these values are among the highest for helical nanographenes.

Herein a class of structurally simple and operationally stable Au(I)-TADF (TADF = thermally activated delayed fluorescence) materials, based on a carbene-metal-amide (CMA) molecular scaffold comprised of sterically bulky N-heterocyclic carbene ligands with N-heterocyclic & pi;-annulation, are reported. These CMA(Au) emitters are thermally stable, adopt coplanar or orthogonal geometry between the carbene and amide ligands, and show strong blue to deep red TADF emissions (466-666 nm) from thermally equilibrated singlet ligand-to-ligand-charge-transfer excited states with emission quantum yields of 0.63-0.99 and radiative decay rate constants of 0.68-3.2 x 10(6) s(-1) in thin film samples at room temperature. The effects of increasing & pi;-extension and orthogonal molecular geometry are similarly manifested in the reduction of both singlet-triplet energy gap and S-1 transition dipole moment. The vacuum-deposited Au(I) organic light-emitting diodes (OLEDs) display superior electroluminescence characterized by ultrahigh brightness up to 300 000 cd m(-2) and external quantum efficiencies (EQEs) up to 26.2% with roll-offs down to 2.6% at 1000 cd m(-2) alongside record-setting device lifetimes (LT95) up to 2082 h. Ultrapure-green TADF-sensitized fluorescent OLEDs employing the CMA(Au) emitter as sensitizer and a multiresonance terminal emitter achieve EQEs of up to 25.3%.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Cyclometalated Pt(II) complexes are popular phosphorescent emitters with color-tunable emissions. To render their practical applications as organic light-emitting diodes emitters, it is required to develop Pt(II) complexes with high radiative decay rate constant and photoluminescence (PL) quantum yield. Here, a general protocol is developed for accurate predictions of emission wavelength, radiative decay rate constant, and PL quantum yield based on the combination of first-principles quantum mechanical method, machine learning, and experimental calibration. A new dataset concerning phosphorescent Pt(II) emitters is constructed, with more than 200 samples collected from the literature. Features containing pertinent electronic properties of the complexes are chosen and ensemble learning models combined with stacking-based approaches exhibit the best performance, where the values of squared correlation coefficients are 0.96, 0.81, and 0.67 for the predictions of emission wavelength, PL quantum yield and radiative decay rate constant, respectively. The accuracy of the protocol is further confirmed using 24 recently reported Pt(II) complexes, which demonstrates its reliability for a broad palette of Pt(II) emitters.

The utilization of triplet metal‐metal‐to‐ligand‐charge‐transfer ( 3 MMLCT) emissions of Pt(II) complexes having a large radiative decay rate is a promising strategy to develop efficient red and deep‐red emitters for practical organic light‐emitting diodes (OLEDs). The panel of robust luminescent dinuclear Pt(II) emitters described here features pyridine‐/pyrazine‐fused N‐heterocyclic carbene‐based cyclometalating ligands and ditopic bis‐ µ 2 ‐formamidinate bridging ligands. These complexes show intramolecular Pt–Pt distances of 2.85–2.87 Å, are thermally stable up to 446 °C, and display strong red and deep‐red 3 MMLCT emission (604–689 nm) with emission quantum yields close to unity. Under laboratory conditions, red and deep‐red OLEDs with these complexes show high external quantum efficiencies (up to 21.3%) and prolonged operational lifetimes (LT 97 up to 2446 h) at an initial luminance of 1000 cd m −2 , highlighting the practicality of these dinuclear Pt(II) emitters in organic optoelectronics application.

Acceleration of singlet-triplet intersystem crossings (ISC) is instrumental in bolstering triplet exciton harvesting of multi-resonance thermally activated delayed fluorescent (MR-TADF) emitters. This work describes a simple gold(I) coordination strategy to enhance the spin-orbit coupling of green and blue BN(O)-based MR-TADF emitters, which results in a notable increase in rate constants of the spectroscopically observed ISC process to 3×10 9  s −1 with nearly unitary ISC quantum yields. Accordingly, the resultant thermally-stable Au I emitters attained large values of delayed fluorescence radiative rate constant up to 1.3×10 5 /1.7×10 5  s −1 in THF/PMMA film while preserving narrowband emissions (FWHM=30–37 nm) and high emission quantum yields (ca. 0.9). The vapor-deposited ultrapure-green OLEDs fabricated with these Au I emitters delivered high luminance of up to 2.53×10 5  cd m −2 as well as external quantum efficiencies of up to 30.3 % with roll-offs as low as 0.8 % and long device lifetimes (LT 60 ) of 1210 h at 1000 cd m −2 .

A critical step in advancing the practical application of copper-based organic light-emitting diodes (OLEDs) is to bridge the large gap between device efficiency and operational stability at practical luminance. Described is a panel of air- and thermally stable two-coordinate Cu I emitters featuring bulky pyrazine- (PzIPr) or pyridine-fused N-heterocyclic carbene (PyIPr*) and carbazole (Cz) ligands with enhanced amide-Cu-carbene bonding interactions. These Cu I emitters display thermally activated delayed fluorescence (TADF) from the 1 LL′CT(Cz→PzIPr/PyIPr*) excited states across the blue to red regions with exceptional radiative rate constants of 1.1–2.2×10 6  s −1 . Vapour-deposited OLEDs based on these Cu I emitters showed excellent external quantum efficiencies and luminance up to 23.6 % and 222 200 cd m −2 , respectively, alongside record device lifetimes (LT 90 ) up to 1300 h at 1000 cd m −2 under our laboratory conditions, highlighting the practicality of the Cu I -TADF emitters.

Metal–organic framework materials are introduced to provide a “solid solution” environment for easy access to metal–metal-to-ligand charge transfer excited states of pincer platinum(ii) complexes and act as photocatalysts.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.