Latest ArticlesNon-fused ring electron acceptors (NFREAs) have a broad application prospect in the commercialization of organic solar cells (OSCs) due to the advantages of simple synthesis and low cost. The selection of intermediate block cores of non-fused frameworks and the establishment of the relationship between molecular structure and device performance are crucial for the realization of high-performance OSCs. Herein, two A-D-A'-D-A type NFREAs namely CBTBO-4F and CBTBO-4Cl, constructed with a novel electron-deficient block unit N-(2-butyloctyl)-carbazole[3,4-c: 5,6-c]bis[1,2,5]thiadiazole (CBT) and bridging unit 4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b: 3,4-b']dithiophene (DTC) coupling with different terminals (IC-2F/2Cl), were designed and synthesized. The two NFREAs feature broad and strong photoresponse from 500 nm to 900 nm due to the strong intramolecular charge transfer characteristics. Compared with CBTBO-4F, CBTBO-4Cl shows better molecular planarity, stronger crystallinity, more ordered molecular stacking, larger van der Waals surface, lower energy level and better active layer morphology, contributing to much better charge separation and transport behaviors in its based devices. As a result, the CBTBO-4Cl based device obtains a higher power conversion efficiency of 10.18% with an open-circuit voltage of 0.80 V and a short-circuit current density of 21.20 mA/cm2. These results not only demonstrate the great potential of CBT, a new building block of the benzothiazole family, in the construction of high-performance organic conjugated semiconductors, but also suggest that the terminal chlorination is an effective strategy to improve device performance.
Among the emitters in powder dusting to visualize the latent fingerprints (LFPs), aggregation-induced emission luminogens (AIEgens) are well employed for their high brightness and resistance to photo-bleaching. However, the serious background interference and low resolution still limit their fast development. Therefore, to further enhance the signal-to-noise ratio in LFPs imaging, especially to improve the analysis for level 3 details, donor-acceptor (D-A) typed AIEgens of DTPA-2,3-P, DTPA-2,5-P and DTPA-2,6-P are designed here. It is observed that strong emission covering from 450 nm to 650 nm can be obtained for all these molecules, especially that a high PLQY value of 10.06% in solids is achieved in DTPA-2,3-P. This is much higher than that of the other two cases (0.80% and 0.51%). By utilizing the DTPA-2,3-P in powder dusting, fluorescence imaging of LFPs can be clearly captured on both smooth and rough substrates. Moreover, confocal laser scanning microscope (CLSM) enables us to achieve high-resolution LFPs imaging in both 2D and 3D views, providing more detailed information of fingerprints pores in width, distance, distribution, and shapes. The results here demonstrate that highly emissive AIEgen of DTPA-2,3-P could be an excellent candidate for the visualization of fingerprints, thus providing the potential application in criminal investigation in the future.
To tackle undesirable shuttle reaction and sluggish reaction kinetics in lithium–sulfur (Li–S) batteries, we develop a porous and high-density oxygen-doped tantalum nitride nanostructure (nano-TaNO) as an efficient catalyst through delicate tailoring. Benefiting from well-defined interior and surface nanopore channels, the nano-TaNO favors abundant sulfur storage, easy electrolyte infiltration and good electrons/Li+ transport. More importantly, high-density O dopant in nano-TaNO not only provides high conductivity, but also promotes polysulfide adsorption/conversion via Li–O chemical interactions and the generation of S3*− radicals to activate additional evolution path from S8 to Li2S. Consequently, the nano-TaNO-based cathode exhibits excellent specific capacity and cyclability even under high sulfur loading condition. These interesting findings suggest the great potential of tantalum nitride and a high amount of anion doping engineering in manipulating intermediates and building high-performance Li−S rechargeable batteries.
The liquid leakage and weak solar absorption capacity of organic phase change materials (PCMs) seriously hinder the efficient utilization of solar energy and thermal energy storage. To address these issues, we prepared nanoporous metal organic framework (Ni-MOF) for the vacuum infiltration of paraffin wax (PW), followed by the coating of solar-absorbing functional polydopamine (PDA) on the surface of PW@MOF for photothermal conversion and storage. As an efficient photon harvester, PDA coating endows PW@MOF/PDA composite PCMs with excellent photothermal conversion and storage properties due to the robust broadband solar absorption capability in the UV–vis region. Resultantly, our prepared PW@MOF/PDA composite PCMs exhibit a high photothermal conversion and storage efficiency of 91.2%, while that of PW@MOF composite PCMs is only zero. In addition, PW@MOF/PDA composite PCMs also exhibit excellent thermal stability, shape stability, energy storage stability, and photothermal conversion stability. More importantly, this coating strategy is universal by integrating different MOFs and solar absorbers, showing the potential to accelerate the major breakthroughs of high-efficiency MOF-based photothermal composite PCMs in solar energy utilization.
Herein, we developed for the first time two carboxylic acid based intrinsic proton conductors (COOH-COF-1 and COOH-COF-2) via pre-assembly approach. The obtained COOH-COF-1 and COOH-COF-2 not only show outstanding chemical and thermal stabilities, but also exhibit superhigh intrinsic proton conductive behaviors. Especially, the intrinsic proton conductivity of COOH-COF-2 is up to 2.6 × 10−3 S/cm at 353 K and 98% RH, which is the highest value among all the reported acid functionalized COFs. This work lights up the way for the rational design of functional COFs with remarkably intrinsic proton conducting performance and related practical applications.
Brookhart-type α-diimine nickel and palladium catalysts have been extensively studied over the past several decades; however, the heterogenization of these metal complexes has received much less attention. In this contribution, we installed a trifluoroborate potassium substituent on an α-diimine framework. The ionic nature of trifluoroborate potassium endowed the α-diimine nickel complex with a strong affinity for the SiO2 support, while its electron-donating nature enhanced the catalyst stability and polyethylene molecular weight. In the presence of only 100 equiv. of Et2AlCl cocatalyst, the SiO2-supported catalyst demonstrated significantly better performance than its homogeneous analog during ethylene polymerization, with extremely high activity (1.42–6.53 × 107 g mol−1 h−1) and high thermal stability. The heterogeneous system led to the formation of high-molecular-weight polyethylenes (Mn 142, 500–732, 800 g/mol), narrow polydispersities (2.18–3.00), tunable branching densities (21–64 per 1000 carbon atoms), and great mechanical properties. Moreover, the efficient copolymerization of ethylene with comonomers such as methyl 10-undecenoate, 6-chloro-1-hexene or 5-hexenylacetate was achieved. These superior properties enabled by the trifluoroborate potassium moiety may inspire its applications in other polymerization catalyst systems.
Opportunities coexist with challenges for the development of carbon-based cathodes with a high energy density applied for zinc ion hybrid capacitors (ZIHCs). In the present study, a facile and effective surface engineering approach is demonstrated to greatly improve the energy storage ability of commercial carbon paper (CP) in ZIHC. Benefiting from the introduced oxygen functional groups, larger surface area and improved surface wettability upon air calcination, the assembled aqueous ZIHC with the functionalized carbon paper (FCP) exhibits a much higher areal capacity of 0.22 mAh/cm2 at 1 mA/cm2, outperforming the counterpart with blank CP by over 5000 times. More importantly, a superior energy density and power density of 130.8 µWh/cm2 and 7460.5 µW/cm2, are respectively delivered. Furthermore, more than 90% of the initial capacity is retained over 10000 cycles. This surface engineering strategy to improve the energy storage capability is potentially applicable to developing a wide range of high-energy carbon electrode materials.
Balancing cost and performance of porous carbon (PC) as anode for lithium-ion battery (LIBs) is the key to effectively promote commercial application. Herein, low-cost N-doped PC (NPC-Ts, T = 600, 750 and 900 ℃) were facilely prepared in batches via one-pot pyrolysis of agar with different carbonization temperature. The NPC-750 with specific surface area of 2914 m2/g and N content of 2.84% exhibits an ultrahigh reversible capacity of 1019 mAh/g at 0.1 A/g after 100 cycles and 837 mAh/g at 1 A/g after 500 cycles. Remarkably, the resulting LIBs exhibit an ultrafast charge-discharge feature with a remarkable capacity of 281 mAh/g at 10 A/g and a superlong cycle life with a capacity retention of 87% after 5000 cycles at 10 A/g. Coupling with LiFePO4 cathode, the fabricated lithium-ion full cells possess high capacity, excellent rate and cycling performances (125 mAh/g at 100 mA/g, capacity retention of 95%, after 220 cycles), highlighting the practicability of this NPC-750 as the anode materials.
To achieve real-time monitoring of humidity in various applications, we prepared facile and ultra-thin CoAl layered double hydroxide (CoAl LDH) nanosheets to engineer quartz crystal microbalances (QCM). The characteristics of CoAl LDH were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectric spectroscopy (XPS), Brunauer–Emmett–Telle (BET), atomic force microscopy (AFM) and zeta potential. Due to their large specific surface area and abundant hydroxyl groups, CoAl LDH nanosheets exhibit good humidity sensing performance. In a range of 11.3% and 97.6% relative humidity (RH), the sensor behaved an ultrahigh sensitivity (127.8 Hz/%RH), fast response (9.1 s) and recovery time (3.1 s), low hysteresis (3.1%RH), good linearity (R2 = 0.9993), stability and selectivity. Besides, the sensor can recover the initial response frequency after being wetted by deionized water, revealing superior self-recovery ability under high humidity. Based on in-situ Fourier transform infrared spectroscopy (FT-IR), the adsorption mechanism of CoAl LDH toward water molecules was explored. The QCM sensor can distinguish different respiratory states of people and wetting degree of fingers, as well as monitor the humidity in vegetable packaging, suggesting excellent properties and a promising application in humidity sensing.
Recently, a novel tetraarylimidazole derivative 2-(benzo[d]thiazol-2-yl)-4-(4,5-bis(4-methoxyphenyl)-1-phenyl-1H-imidazol-2-yl)-phenol (be called MHBT herein) was architectured by our research group showing the fascinating synergy of aggregation-induced emission (AIE) characteristic, excited-state intramolecular proton transfer (ESIPT) mechanism and intramolecular charge transfer (ICT) effect. Nevertheless, a detailed and reasonable interpretation of its mechanisms both in theory is urgently needed. Consequently, to unveil the working mechanism meticulously, herein, we tactfully applied density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods to illuminate the underlying mechanisms in different solvent conditions. After optimizing the structures, the geometric parameters of hydrogen bonds (HBs), the infrared (IR) vibrational spectrum, the reduced density gradient (RDG) isosurfaces were calculated in detail, vividly explaining how the enhancement of HBs behaved as the driving force to proceed ESIPT process. Simultaneously, the frontier molecular orbitals (FMOs) combined with the potential energy curves (PECs) were conducted to interpretate the role and character of ICT and ESIPT in molecule MHBT. Further, the PECs of MHBT for dihedral angles in different organic solvents were calculated to compare the dominant torsion degree, rationalizing the AIE phenomenon from the view of the restriction of intramolecular rotation process. This work may well underpin the understanding of the interaction between different mechanisms in fluorescent dyes and thereby provide meaningful guideline for the design and construction of ideal molecules
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