Engineering Lewis-Acid Defects on ZnO Quantum Dots by Trace Transition-Metal Single Atoms for High Glycerol-to-Glycerol Carbonate Conversion.

Efficient conversion of biomass wastes into valuable chemicals has been regarded as a sustainable approach for green and circular economy. Herein, a highly efficient catalytic conversion of glycerol (Gly) into glycerol carbonate (GlyC) by carbonylation with the commercially available urea is presented using low-cost transition metal single atoms supported on zinc oxide quantum dots (M1-ZnO QDs) as a catalyst without using any solvent. A facile one-step wet chemical synthesis allows various types of metal single atoms to simultaneously dope and introduce Lewis-acid defects in the ZnO QD structure. It is found that doping with a trace amount of isolated metal atoms greatly boosts the catalytic activity with Gly conversion of 90.7%, GlyC selectivity of 100.0%, and GlyC yield of 90.6%. Congruential results from both Density Functional Theory (DFT) and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) studies reveal that the superior catalytic performance can be attributed to the enriched Lewis acid sites that endow optimal adsorption, formation of the intermediate for coupling between urea and Gly, and desorption of GlyC. Moreover, the tiny size of ZnO QDs efficiently promotes the accessibility of these active sites to the reactants.

Rational Design of Fe Single Sites Supported on Hierarchical Zeolites via Atomic Layer Deposition for Few-Walled Carbon Nanotube Production.

Metal single-site catalysts have recently played an essential role in catalysis due to their enhanced activity, selectivity, and precise reaction control compared to those of conventional metal cluster catalysts. However, the rational design and catalytic application of metal single-site catalysts are still in the early stages of development. In this contribution, we report the rational design of Fe single sites incorporated in a hierarchical ZSM-5 via atomic layer deposition (ALD). The designer catalysts demonstrated highly dispersed Fe species, predominantly stabilized by oxygen atoms in the zeolite framework at terminal, isolated, and vicinal silanol groups within the micropores and external surfaces of the zeolite. The successful incorporation of highly thermally stable and uniform Fe single sites into hierarchical zeolite through ALD represents a significant advancement in few-walled carbon nanotube production. The inner and outer diameters of produced CNTs are approximately 4.4 ± 2.4 and 8.6 ± 1.8 nm, respectively, notably smaller than those produced via traditional impregnated catalysts. This example emphasizes the concept of rational design of a single Fe site dispersed on a hierarchical ZSM-5 surface, which is anticipated to be a promising catalyst for advancing catalytic applications.

Unraveling the Electrocatalytic Activity in HMF Oxidation to FDCA by Fine-Tuning the Degree of NiOOH Phase Over Ni Nanoparticles Supported on Graphene Oxide.

The development of an efficient electrocatalyst for HMF oxidation to FDCA has been in the early stages. Herein, the NiNPs/GO-Ni-foam is fabricated as an electrocatalyst for FDCA production. However, the electrocatalytic performance of the untreated NiNPs/GO-Ni-foam is observed with moderate Faradaic efficiency (FE) (73.0%) and FDCA yield (80.2%). By electrochemically treating the NiNPs/GO-Ni-foam in an alkaline solution with positive potential at different treatment durations, the degree of NiOOH on metal surfaces is changed. The distinctive electrocatalytic activity obtained when using the different NiOOH degrees allows to understand the crucial impact of NiOOH species in HMF electrooxidation. Enhancing the portion of the NiOOH phase on the electrocatalyst surface improves electrocatalytic activity in terms of FE and FDCA yield up to 94.8±4.8% and 86.9±4.1%, respectively. Interestingly, as long as the NiOOH portion on the electrocatalyst surface is preserved or regenerated, the electrocatalyst performance can be intact even after several catalytic cycles. The theoretical study via density functional theory (DFT) also agrees with the experimental observations and confirms that the NiOOH phase facilitates the electrochemical transformation of HMF to FDCA through the HMFCA pathway, and the potential limiting step of the overall reaction is the oxidation of FFCA to FDCA.

General Pyrolysis for High-Loading Transition Metal Single Atoms on 2D-Nitro-Oxygeneous Carbon as Efficient ORR Electrocatalysts.

Single-atom catalysts (SACs) possess the potential to involve the merits of both homogeneous and heterogeneous catalysts altogether and thus have gained considerable attention. However, the large-scale synthesis of SACs with rich isolate-metal sites by simple and low-cost strategies has remained challenging. In this work, we report a facile one-step pyrolysis that automatically produces SACs with high metal loading (5.2-15.9 wt %) supported on two-dimensional nitro-oxygenated carbon (M1-2D-NOC) without using any solvents and sacrificial templates. The method is also generic to various transition metals and can be scaled up to several grams based on the capacity of the containers and furnaces. The high density of active sites with N/O coordination geometry endows them with impressive catalytic activities and stability, as demonstrated in the oxygen reduction reaction (ORR). For example, Fe1-2D-NOC exhibits an onset potential of 0.985 V vs RHE, a half-wave potential of 0.826 V, and a Tafel slope of -40.860 mV/dec. Combining the theoretical and experimental studies, the high ORR activity could be attributed its unique FeO-N3O structure, which facilitates effective charge transfer between the surface and the intermediates along the reaction, and uniform dispersion of this active site on thin 2D nanocarbon supports that maximize the exposure to the reactants.

Photochemical engineering unsaturated Pt islands on supported Pd nanocrystals for a robust pH-universal hydrogen evolution reaction.

The rational design of heterostructured nanocrystals (HNCs) is of great significance for developing highly efficient hydrogen evolution reaction (HER) electrocatalysts. However, a significant challenge still lies in realizing the controllable synthesis of desired HNCs directly onto a support and exploring their structure-activity-dependent HER performance. Herein, we reported various controllable Pd7@Ptx core-shell HNCs with optimal hybrid structures via a photochemical deposition strategy. The growth patterns of a Pt shell can be finely controlled by adjusting the growth kinetics, resulting in a varying deposition rate. In particular, the as-prepared Pd7@Pt3 HNCs with a Pt shell in the Stranski-Krastanov mode showed the best performances over a wide pH range media, delivering low overpotentials of 33, 18 and 49 mV, resulting in a catalytic current density of 10 mA cm-2 at a low effective catalyst loading of 0.021 mg cm-2. The resulting Tafel slopes were 23.1, 52.6 and 42.7 mV dec-1 in 0.5 M H2SO4, 1.0 M phosphate-buffered saline (PBS) and 1.0 M KOH electrolyte, respectively. It was found that the increased fraction of unsaturated coordination of Pt islands in the resultant material is the key to the enhanced and robust HER activity, which has been confirmed through density functional theory (DFT) calculations. This strategy could be extended to the rational design and synthesis of other heterostructured catalysts for energy conversion and storage.

Enhanced Electrocatalytic CO2 Reduction Reactivity of S- and N-Doped Fe-Embedded Graphene.

In this work, we studied the reaction mechanisms for CO2 reduction reaction (CRR) on the iron-doped graphene and its coordinating sulfur (S) and nitrogen (N) variants, FeNn S4-n (n=1-4), using density functional theory calculations. Our results revealed that the electronic property and catalytic reactivity of the surfaces can be tuned by varying the N and S atoms ratio. The CRR activities of the mixed surfaces, FeN3 S1 , FeN2 S2 , and FeN1 S3 , were better than FeN4 and FeS4 , where the absolute value of the limiting potential of the mixed surface decreased by 0.3 V. Considering the stability, we suggest FeN3 S surface to be favorable for CRR. For the bare surfaces, we found a positive linear correlation between the magnetic moment and the charge of Fe metal. For these surfaces, the reduction of CO (*CO+(H+ +e- )→*CHO) was important in deciding the limiting potential. We found that the adsorption energy of CO displayed a volcano relationship with the magnetic moment of the Fe atom. The study showed that the change of local coordinating structure around the Fe atom could modify the electronic and magnetic properties of the active Fe center and improve the CRR activity performance.

Efficient exploration of transition-metal decorated MXene for carbon monoxide sensing using integrated active learning and density functional theory.

The urgent demand for chemical safety necessitates the real-time detection of carbon monoxide (CO), a highly toxic gas. MXene, a 2D material, has shown potential for gas sensing applications (e.g., NH3, NO, SO2, CO2) due to its high surface accessibility, electrical conductivity, stability, and flexibility in surface functionalization. However, the pristine MXene generally exhibits poor interaction with CO; still, transition metal decoration can strengthen the interaction between CO and MXene. This study presents a high-throughput screening of 450 combinations of transition-metal (TM) decorated MXene (TM@MXene) for CO sensing applications using an integrated active learning (AL) and density functional theory (DFT) screening pipeline. Our AL pipeline, adopting a crystal graph convolutional neural network (CGCNN) as a surrogate model, successfully accelerates the screening of CO sensor candidates with minimal computational resources. This study identifies Sc@Zr3C2O2 and Y@Zr3C2O2 as the optimal TM@MXene candidates with promising CO sensing performance regarding the screening criteria of recovery time, surface stability, charge transfer, and sensitivity to CO. The proposed AL framework can be extended for property finetuning in the combinatorial chemical space.

Unraveling the Adsorption Behavior of Thymol on Carbon and Silica Nanospheres for Prolonged Antibacterial Activity: Experimental and DFT Studies.

Functionalization of thymol (Thy) on nanocarriers is a key step in achieving prolonged antimicrobial activity. This requires nanomaterials with uniform particle diameters and suitable thymol sorption. Herein, hollow carbon (HC) and SiO2-carbon core-shell (SiO2@C) were investigated due to their diverse morphologies and ease of surface modification. HC (14 ± 1 nm size) and SiO2@C (10 ± 1.5 nm size) were synthesized by the Stöber method before thymol was loaded by incipient wetness impregnation. Nanoparticle physicochemical properties were characterized by advanced techniques, including X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS). Adsorption energies of thymol on the carbon and SiO2 surfaces were elucidated by density functional theory (DFT) simulations. Moreover, the in vitro thymol release profiles and antibacterial activity were evaluated. The experimental results indicated that the oxy-carbon surface species of HC led to longer thymol release profiles than the -OH group of SiO2@C. The DFT calculations revealed that the weaker physical interaction of thymol on HC was better for drug release than that on SiO2@C. Thus, a longer thymol release profile of HC with hollow structures showed better antibacterial performance against Gram-positive bacteria Staphylococcus aureus than that of SiO2@C with core-shell structures. This work confirms the important role of carbon morphology and specific functional groups in thymol release profiles for the further development of inhibition products.

Impact of exposed crystal facets on oxygen reduction reaction activity in zeolitic imidazole frameworks.

ZIF-67 is a representative type of metal-organic framework (MOF) developed for the oxygen reduction reaction (ORR) owing to its robust structure in alkaline electrolytes and the presence of the redox-active Co2+ species in the structure. In this work, the improvement of the ORR electrolytic performance of ZIF-67 in its pure phase by optimization of its crystal morphology and crystal facets has been presented. ZIF-67 nanocubes exhibit higher ORR activity than their bulk crystals. The enriched (100) facet in the nanocube crystals provides a higher number of exposed Co2+ sites resulting in improved ORR performances. Moreover, DFT study suggests a distinguished mechanism in the (100) facet highlighting the importance of crystal facets in electrochemical performances.

Data-Driven Discovery of Graphene-Based Dual-Atom Catalysts for Hydrogen Evolution Reaction with Graph Neural Network and DFT Calculations.

The flexible tuning ability of dual-atom catalysts (DACs) makes them an ideal system for a wide range of electrochemical applications. However, the large design space of DACs and the complexity in the binding motif of electrochemical intermediates hinder the efficient determination of DAC combinations for desirable catalytic properties. A crystal graph convolutional neural network (CGCNN) was adopted for DACs to accelerate the high-throughput screening of hydrogen evolution reaction (HER) catalysts. From a pool of 435 dual-atom combinations in N-doped graphene (N6Gr), we screened out two high-performance HER catalysts (AuCo@N6Gr and NiNi@N6Gr) with excellent HER, electronic conductivity, and stability using the combination of CGCNN and density functional theory (DFT). Furthermore, comprehensive DFT studies were conducted on these two catalysts to confirm their outstanding reaction kinetics and to understand the cooperative effect between the metal pair for HER. To obtain ideal hydrogen binding in AuCo, the inert Au weakens the strong hydrogen binding of Co, while for NiNi, the two weakly binding Ni cooperate. The present protocol was able to select the two catalysts with different physical origins for HER and can be applied to other DAC catalysts, which should hasten catalyst discovery.

New Folding 2D-Layered Nitro-Oxygenated Carbon Containing Ultra High-Loading Copper Single Atoms.

The discoveries of 2D nanomaterials have made huge impacts on the scientific community. Their unique properties unlock new technologies and bring significant advances to diverse applications. Herein, an unprecedented 2D-stacked material consisting of copper (Cu) on nitro-oxygenated carbon is disclosed. Unlike any known 2D stacked structures that are usually constructed by stacking of separate 2D layers, this material forms a continuously folded 2D-stacked structure. Interestingly, advanced characterizations indicate that Cu atoms inside the structure are in an atomically-dispersed form with extraordinarily high Cu loading up to 15.9 ± 1.2 wt.%, which is among the highest reported metal loading for single-atom catalysts on 2D supports. Facile exfoliation results in thin 2D nanosheets that maximize the exposure of the unique active sites (two neighboring Cu single atoms), leading to impressive catalytic performance, as demonstrated in the electrochemical oxygen reduction reaction.

Metal-organic framework MIL-100(Fe) as a promising sensor for COVID-19 biomarkers detection.

The development of fast and non-invasive techniques to detect SARS-CoV-2 virus at the early stage of the infection would be highly desirable to control the COVID-19 outbreak. Metal-organic frameworks (MOFs) are porous materials with uniform porous structures and tunable pore surfaces, which would be essential for the selective sensing of the specific COVID-19 biomarkers. However, the use of MOFs materials to detect COVID-19 biomarkers has not been demonstrated so far. In this work, for the first time, we employed the density functional theory calculations to investigate the specific interactions of MOFs and the targeted biomarkers, in which the interactions were confirmed by experiment. The five dominant COVID-19 biomarkers and common exhaled gases are comparatively studied by exposing them to MOFs, namely MIL-100(Al) and MIL-100(Fe). The adsorption mechanism, binding site, adsorption energy, recovery time, charge transfer, sensing response, and electronic structures are systematically investigated. We found that MIL-100(Fe) has a higher sensing performance than MIL-100(Al) in terms of sensitivity and selectivity. MIL-100(Fe) shows sensitive to COVID-19 biomarkers, namely 2-methylpent-2-enal and 2,4-octadiene with high sensing responses as 7.44 x 105 and 9 x 107 which are exceptionally higher than those of the common gases which are less than 6. The calculated recovery times of 0.19 and 1.84 x 10-4 s are short enough to be a resuable sensor. An experimental study also showed that the MIL-100(Fe) provides a sensitivity toward 2-methylpent-2-enal. In conclusion, we suggest that MIL-100(Fe) could be used as a potential sensor for the exhaled breath analysis. We hope that our research can aid in the development of a biosensor for quick and easy COVID-19 biomarker detection in order to control the current pandemic.

Understanding the interaction between transition metal doping and ligand atoms of ZnS and ZnO monolayers to promote the CO2 reduction reaction.

Single-atom catalysts (SACs) obtained by doping transition metal (TM) atoms into stable monolayers are a promising way to improve the CO2 reduction reaction (CRR) performance. In this work, we theoretically investigated the effect of ligand atoms around the doped TM (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) in ZnO and ZnS for promoting the CRR performance. We found that the ligand atoms around the TM can influence its oxidation state and the electronic properties of the SACs, thus affecting their CRR activity. Due to the smaller charge transfer between the TM and substrate for TM-ZnS compared to TM-ZnO, the TM binding is weaker for the former. In addition, the more negatively charged oxygen ligand atoms in TM-ZnO interact with reaction intermediates, resulting in CRR products with less electron transfer. Pristine ZnS and ZnO monolayers can produce HCOOH but require a high limiting potential (UL) of about -1.2 V. Doping with TMs can reduce UL compared to the pristine surface. At the same time, the ligand can alter the preferred CRR pathway and product selectivity. We found that Mn-ZnS is selective to the CH4 product with a UL of only -0.29 V, which is a nearly 1 V improvement in the UL compared to ZnS.

Adsorption and dehydration of ethanol on isomorphously B, Al, and Ga substituted H-ZSM-5 zeolite: an embedded ONIOM study.

Dehydration reactions are important in the petroleum and petrochemical industries, especially for the feedstock production. In this work, the catalytic activity of zeolites with different acidities for the dehydration of ethanol to ethylene and diethylether is investigated by density functional calculations on cluster models of three isomorphous B, Al, and Ga substituted H-ZSM-5 zeolites. Both unimolecular and bimolecular mechanisms are investigated. Detailed reaction profiles for the dehydration reaction, assuming either a stepwise or a concerted mechanism, were calculated by using the ONIOM(MP2:M06-2X) + SCREEP method. The adsorption energies of ethanol are -21.6, -28.1, and -27.7 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The activation energies for the rate-determining step of the unimolecular concerted mechanism for the ethylene formation are 48.5, 42.6, and 43.6 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The activation energies for the ethoxy formation as the rate-determining step for the bimolecular formation of diethylether are 42.3, 40.0, and 41.1 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The results indicate that the catalytic activities for the dehydration of ethanol decrease in the order H-[Al]-ZSM-5 ~ H-[Ga]-ZSM-5 > H-[B]-ZSM-5. Besides the acid strength, the zeolite framework affects the reaction by stabilizing the reaction intermediates, leading to more stable adsorption complexes and lower activation barriers.

Ti4-Decorated B/N-doped graphene as a high-capacity hydrogen storage material: a DFT study.

The adsorption properties of the hydrogen atom on our newly designed materials were investigated using density functional theory (DFT) calculations, focusing on the role of dopants in modulating the binding properties of the metal. We proposed decorating Ti4 on pristine, B- and N-doped graphene surfaces for preparing a large-capacity hydrogen-storage device. Computational results indicate that the doping of B on graphene enhances the interaction between the metal cluster and the supporting substrate with a very strong binding energy of -6.45 eV, which is the strongest interaction among our proposed catalysts. This binding energy prevents the aggregation and formation of Ti-metal clusters. Dissociative chemisorption of the first H2 molecule occurs on all materials. Metal hydrides preferentially exhibit strong hybridization between the H-1s and Ti-3d orbitals. Furthermore, Ti4 decorated B-graphene is the most effective, with a high capacity of hydrogen adsorption which could be released under practical conditions. We confirmed that eight H2 molecules could stably adsorb on Ti4/BGr with six reversible hydrogen adsorptions. Our proposed B-doped graphene-based material, Ti4/BGr, offers high cluster-stability on the substrate with high-capacity hydrogen storage compared to various other surfaces in the previous work. Therefore, Ti4 decorated B-graphene is a promising candidate material for use as a reversible hydrogen storage material.

Highly Active Chromium Complexes Supported by Constrained Schiff-Base Ligands for Cycloaddition of Carbon Dioxide to Epoxides.

Novel constrained Schiff-base ligands (inden) were developed based on the well-known salen ligands. Chromium complexes supported by the constrained inden ligands were successfully synthesized and used as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2). The catalyst having tert-butyl (tBu) groups as substituents in combination with tetrabutylammonium bromide (TBAB) as a cocatalyst exhibited very high catalytic activity with a turnover frequency of up to 14800 h-1 for the conversion of CO2 and propylene oxide into propylene carbonate exclusively at 100 °C and 300 psi of CO2 under solvent-free conditions. The catalyst was found to be highly active for various epoxide substrates to produce terminal cyclic carbonates in 100% selectivity.

Effect of Water Microsolvation on the Excited-State Proton Transfer of 3-Hydroxyflavone Enclosed in γ-Cyclodextrin.

The effect of microsolvation on excited-state proton transfer (ESPT) reaction of 3-hydroxyflavone (3HF) and its inclusion complex with γ-cyclodextrin (γ-CD) was studied using computational approaches. From molecular dynamics simulations, two possible inclusion complexes formed by the chromone ring (C-ring, Form I) and the phenyl ring (P-ring, Form II) of 3HF insertion to γ-CD were observed. Form II is likely more stable because of lower fluctuation of 3HF inside the hydrophobic cavity and lower water accessibility to the encapsulated 3HF. Next, the conformation analysis of these models in the ground (S0) and the first excited (S1) states was carried out by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, respectively, to reveal the photophysical properties of 3HF influenced by the γ-CD. The results show that the intermolecular hydrogen bonding (interHB) between 3HF and γ-CD, and intramolecular hydrogen bonding (intraHB) within 3HF are strengthened in the S1 state confirmed by the shorter interHB and intraHB distances and the red-shift of O-H vibrational modes involving in the ESPT process. The simulated absorption and emission spectra are in good agreement with the experimental data. Significantly, in the S1 state, the keto form of 3HF is stabilized by γ-CD, explaining the increased quantum yield of keto emission of 3HF when complexing with γ-CD in the experiment. In the other word, ESPT of 3HF is more favorable in the γ-CD hydrophobic cavity than in aqueous solution.

Red to orange thermally activated delayed fluorescence polymers based on 2-(4-(diphenylamino)-phenyl)-9H-thioxanthen-9-one-10,10-dioxide for efficient solution-processed OLEDs.

Most highly efficient thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs) are multi-layer devices fabricated by thermal vacuum evaporation techniques, which are unfavorable for real applications. However, there are only a few reported examples of efficient solution-processed TADF OLEDs, in particular TADF polymer OLEDs. Herein, a series of solution-processable TADF conjugated polymers (PCTXO/PCTXO-Fx (x = 25, 50 and 75)) were designed and synthesized by copolymerization of 2-(4-(diphenylamino)-phenyl)-9H-thioxanthen-9-one-10,10-dioxide (TXO-TPA) as a red/orange emissive TADF unit, 9,9'-((fluorene-9,9-diyl)-bis(octane-8,1-diyl))-bis(3,6-di-tert-butylcarbazole) as host/hole-transporting unit and 2,7-N-(heptadecan-9-yl)carbazole as a conjugated linker and solubilizing group. They possessed a conjugated backbone with donor TPA-carbazole/fluorene moieties and a pendent acceptor 9H-thioxanthen-9-one-10,10-dioxide (TXO) forming a twisted donor-acceptor structure. These polymers in neat films displayed red/orange color emissions (601-655 nm) with TADF properties, proved by theory calculations and transient PL decay measurements. Their hole-transporting capability was improved when the content of 9,9'-((fluorene-9,9-diyl)-bis(octane-8,1-diyl))-bis(3,6-di-tert-butylcarbazole) within the polymers increased. All polymers were successfully employed as emitters in solution-processed OLEDs. In particular, the doped OLED fabricated with PCTXO exhibited an intense deep orange emission at 603 nm with the best electroluminescence performance (a maximum external quantum efficiency 10.44%, a maximum current efficiency of 14.97 cd A-1 and a turn-on voltage of 4.2 V).

The improvement in hole-transporting and electroluminescent properties of diketopyrrolopyrrole pigment by grafting with carbazole dendrons.

Diketopyrrolopyrrole (DPP) pigments are essential and have been intensively exploited as building-blocks for the synthesis of organic semiconducting polymers and small molecules; however, DPP derivatives as emissive materials for electroluminescent (EL) devices have rarely been explored. In this work, a series of new DPP derivatives grafted with carbazole dendrons in a non-conjugated fashion using an amide linkage was designed to improve the performance of DPP in EL devices. Three DPP derivatives (G0DPP, G1DPP and G2DPP) bearing di(p-chlorophenyl)-DPP (Pigment Red 254) as the core substituted with a hexyl chain, N-hexyl carbazole and N-hexyl-N'-9,3':6',N''-tercarbazole, respectively, were synthesized to afford improved hole-transporting properties without affecting the photophysical and electronic properties of the DPP core. The synthesized DPP derivatives displayed an intense yellow fluorescence emission peaked at 536 nm with an absolute photoluminescence quantum yield close to unity in solution. The hole-transporting capability of molecules was improved when carbazole dendrons were incorporated, which increased with an increase in the generation of substituent carbazole dendrons in the order of G0DPP < G1DPP < G2DPP. Significantly, the use of G2DPP, showing the highest hole mobility, in an EL device yielded a strong and stable yellow emission peaked at 556 nm (CIE x, y color coordinates of (0.45, 0.53)) with a brightness of 3060 cd m-2, maximum luminous efficiency of 9.24 cd A-1 and a maximum EQE of 3.11%.

A Simple and Strong Electron-Deficient 5,6-Dicyano[2,1,3]benzothiadiazole-Cored Donor-Acceptor-Donor Compound for Efficient Near Infrared Thermally Activated Delayed Fluorescence.

Despite the success of thermally activated delayed fluorescent (TADF) materials in steering the next generation of organic light-emitting diodes (OLEDs), effective near infrared (NIR) TADF emitters are still very rare. Here, we present a simple and extremely high electron-deficient compound, 5,6-dicyano[2,1,3]benzothiadiazole (CNBz), as a strong electron-accepting unit to develop a sufficiently strong donor-acceptor (D-A) interaction for NIR emission. End-capping with the electron-donating triphenylamine (TPA) unit created an effective D-A-D type system, giving rise to an efficient NIR TADF emissive molecule (λem =750 nm) with a very small ΔEST of 0.06 eV. The electroluminescent device using this NIR TADF emitter exhibited an excellent performance with a high maximum radiance of 10020 mW Sr-1 m-2 , a maximum EQE of 6.57% and a peak wavelength of 712 nm.