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Portevin–Le Chatelier effect, associated with dynamic strain aging, is widely found in various alloys, and the maximum serration magnitude from the tensile stress–strain curve can be considered as the point closest to the failure threshold. Due to the difficulty to define solute and solvent atoms in multicomponent alloys, it is a great challenge to explore the serration mechanism. In this study, the atoms that play the role of pinning are defined as solute atoms. Aided by mean-field theory, an in situ pinning model coupled with the twinning effect in a CoNiV alloy with low stacking fault energies is successfully established, which can well predict the failure threshold, i.e., the maximum serration magnitude. The present study paves a new way to correlate the serration dynamics and in situ pinning, and further predicts the failure threshold upon loading for multicomponent high- and medium-entropy alloys. [ABSTRACT FROM AUTHOR]

White organic light‐emitting diodes (WOLEDs) have been regarded as the candidates for next‐generation flat‐panel displays and solid‐state lighting due to their low cost. However, it is still challenging to achieve two‐component WOLEDs with high efficiency, high color index (CRI), and long lifetime. Here, high‐performance all‐fluorescence WOLEDs based on a blue fluorescent emitter and an orange thermally activated delayed fluorescent (TADF) emitter are demonstrated. The optimized all‐fluorescence WOLED with two EMLs presents the maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 23.4%, 40.2 cd A−1, and 33.2 lm W−1, corresponding to a maximum CRI value of 83.1 and Commission Internationale de L'Eclairage (CIE) coordinate of (0.30, 0.31). To further improve the device stability, the all‐fluorescence WOLEDs with three EMLs and tandem structure are constructed, respectively. Under the premise of ensuring efficiency, in going from the two‐EMLs to the three‐EMLs and the tandem structure, the LT50 (time to 50% of the initial luminance) of all‐fluorescence WOLEDs increase from 601 to 714 h and 1622 h at an initial luminance of 1000 cd m−2. These strategies and results present new insight into the design of all‐fluorescence WOLEDs with high efficiency, high CRI, and extended lifetime. [ABSTRACT FROM AUTHOR]

The main obstacles to promoting the commercialization of perovskite solar cells (PSCs) include their record power conversion efficiency (PCE), which still remains below the Shockley–Queisser limit, and poor long‐term stability, attributable to crystallographic defects in perovskite films and open‐circuit voltage (Voc) loss in devices. In this study, potassium (4‐tert‐butoxycarbonylpiperazin‐1‐yl) methyl trifluoroborate (PTFBK) was employed as a multifunctional additive to target and modulate bulk perovskite defects and carrier dynamics of PSCs. Apart from simultaneously passivating anionic and cationic defects, PTFBK could also optimize the energy‐level alignment of devices and weaken the interaction between carriers and longitudinal optical phonons, resulting in a carrier lifetime of greater than 3 μs. Furthermore, it inhibited non‐radiative recombination and improved the crystallization capacity in the target perovskite film. Hence, the target rigid and flexible p‐i‐n PSCs yielded champion PCEs of 24.99 % and 23.48 %, respectively. More importantly, due to hydrogen bonding between formamidinium and fluorine, the target devices exhibited remarkable thermal, humidity, and operational tracking at maximum power point stabilities. The reduced Young's modulus and residual stress in the perovskite layer also provided excellent bending stability for flexible target devices. [ABSTRACT FROM AUTHOR]

A simple strategy to simultaneously achieve fast reverse intersystem crossing (RISC) and low non‐radiative decay rates in thermally activated delayed fluorescence (TADF) emitters is still lacking. Here, the green TADF emitters containing aromatic ketones and prepared D‐Ph and D‐PhCz containing different amounts of deuterium are deuterated to study the mechanism of deuterium on the performance improvement of TADF devices. Due to the heavy atom effect of deuterium, the non‐radiative transition rate constant (knr) of D‐Ph and D‐PhCz decreases. Most importantly, deuterium reduces the reorganization energy (λ) of (T1‐S1), which greatly improves the reverse intersystem crossing rate constant (kRISC) and the exciton utilization efficiency. The results show that the external quantum efficiency of D‐Ph and D‐PhCz increases to 25.69% and 24.92%, respectively. This study provides a simple and efficient strategy for reducing non‐radiative energy loss and increasing kRISC to achieve high‐performance TADF emitters. [ABSTRACT FROM AUTHOR]

The development of efficient and stable electroluminescent devices is one of the formidable challenges in the study of organic light-emitting diodes (OLEDs). Herein, three donor (D) and acceptor (A) connection arrangements in dual-D–A thioxanthone derivatives (ADAD, ADDA, DAAD) are investigated to parse their different intramolecular charge transfer (ICT) excited state features and their effects on intersystem crossing (ISC)–reverse intersystem crossing (RISC) as well as radiative transition processes. Compared to two others, the alternate-D–A structure (ADAD) affords nearly isoenergetic singlet and triplet states with weak ICT characters and strong spin–orbit couplings, suppressing the non-radiative transition and inducing multiple ISC–RISC cycles to achieve the highest photoluminescence quantum yield and RISC rate constant. Logically, OLED devices based on this emitter enable ultra-high exciton utilization efficiency of nearly 100%, an external quantum efficiency of 28.93%, and excellent device stability (with an estimated LT50 of about 2303 h at 1000 cd m−2). These findings could open a wide opportunity for a new class of organic light-emitting diodes for various applications. [ABSTRACT FROM AUTHOR]

The use of the emerging hybrid analog-digital structure for future millimeter-wave communications has attracted much attention. Although this structure can reduce the power consumption considerably, the spatial covariance matrix (SCM), as the core of subspace-based direction of arrival (DOA) estimation algorithms, cannot be obtained directly. The beam sweeping algorithm (BSA) was proposed for SCM reconstruction from compressed measurements. However, the BSA is computationally intensive owing to the high-dimensional matrix-to-matrix multiplication and matrix inversion. To address this issue, a BSA algorithm with high accuracy and low computational-cost using the submatrix multiplication (BSASM) is proposed in this paper. By appropriately adjusting the weight, which consists of a switch and a phase shifter, connected to each antenna, the SCM can be accurately reconstructed with low-dimensional matrix-to-vector multiplication and 2-dimensional matrix inversion, thus reducing the computational-cost significantly. After SCM reconstruction, various DOA estimation algorithms can be exploited to obtain the DOA information. Simulation experiments are conducted to verify the performance of the proposed algorithm. The results indicate that using a substantially lower computational-cost, BSASM can reconstruct SCM more accurately than BSA. [ABSTRACT FROM AUTHOR]

To achieve high exciton utilization of organic light-emitting diodes, the construction of donor–acceptor (D–A) molecules with a "hot exciton" feature has been proved to be an effective strategy. Herein, two novel benzothiadiazole based D–A–D′ type "hot exciton" materials, TPA-BT-PBI and TPA-BT-IM, have been designed and synthesized for red OLEDs. The TPA-BT-PBI and TPA-BT-IM based non-doped devices exhibit maximum external quantum efficiency (EQEmax) values of 2.78% and 5.11%, respectively. The EQEmax of TPA-BT-PBI and TPA-BT-IM based doped devices increased significantly up to 7.78% and 9.41%, respectively. The experimental results demonstrate that the D–A fragment determines its optical properties and incorporating the D′ group is important to improve charge transfer balance and realize high brightness. [ABSTRACT FROM AUTHOR]

In this work, a new vacuum-processable non-fullerene acceptor CBD was designed using a D–A strategy for the first time, which exhibits a low optical bandgap of 1.41 eV, and guarantees efficient light harvesting in the visible-NIR region. The optimal CBD-based vacuum-deposited organic solar cells with a planar heterojunction architecture delivered a PCE of 0.86% with a low energy loss of 0.63 eV, which indicates the great potential of D–A-type non-fullerene acceptors for vacuum-deposited solar cells. [ABSTRACT FROM AUTHOR]

The first mixed thieno-S,S-dioxide-furan acenes (BTOBFs) were constructed by simple oxidation of benzo[4,5]thieno-[3,2-b]benzofurans (BTBFs). After oxidation, the absorption and emission peaks of the compounds undergo a significant red shift, and fluorescence quantum yields (Φf = 0.23–0.90) are increased several to several tens of times thanks to the more rigid and more π-extended molecular backbone as well as significant intramolecular charge transfer. F-BTOBF and F,Cl-BTOBF displayed somewhat low device performance with external quantum efficiency (EQE) of 0.72–0.78% yet desirable blue emission. However, when we introduce strong electron-donating groups such as carbazolyl or triphenylamino group into BTOBFs to further tune the electronic properties, the resulting compounds 2-NPhCz-BTOBF and 2-TPA-BTOBF exhibit not only much red shift in absorption and fluorescence, but also significant improvement in hole mobility. As a result, these two compounds displayed much better device performance with respectable EQEs of 5.82–6.49%, low turn-on voltage less than 3 V and lower efficiency roll-off. Therefore, for the first time, this work reports the huge potential of mixed thieno-S,S-dioxide-furan acenes as blue to green emitters for high-performance OLEDs. [ABSTRACT FROM AUTHOR]

High efficiency white organic light-emitting diodes (WOLEDs) with simple device architecture are desirable for next-generation light sources. However, it is still challenging in the construction of high-performance WOLEDs with a simple device structure. Based on a thermally activated delayed fluorescence (TADF) blue emitter 2SPAc-MPM and a TADF yellow emitter TXO-TPA, high performance two-color WOLEDs with simple device architecture are demonstrated. Benefiting from efficient energy transfer and wide coverage over the visible spectrum, optimized WOLED devices that have a single emitting layer (s-EML) provide a maximum color rendering index (CRI) and maximum external quantum efficiency (EQE) of 78.1 and 21.8%, respectively. More importantly, with multiple emitting layers (m-EMLs), a maximum EQE of 14.5% and a high CRI of 90.7 can be achieved. These results are among the best for the two-color WOLEDs with two TADF emitters. [ABSTRACT FROM AUTHOR]

Asphaltene deposition can cause serious problems during petroleum refinery. In this paper, oil-soluble MAC series asphaltene dispersants with comblike structure were synthesized by free- radical polymerization and amination. The asphaltene deposition inhibition was investigated by determining the flocculation onset of blended crude oil (Tahe: Northern Xinjiang = 20:80 (w/w)) and conducting dynamic thermal deposition experiment. The results showed that MAC3 had the best performance and the flocculation onset of crude oil increased from −20.5 to 3.89 when the dosage of MAC3 was 150 mg/L. The anti-scaling rate of MAC3 was 60% in dynamic thermal deposition experiment of blended crude oil. [ABSTRACT FROM AUTHOR]

β-cyclodextrin derivative intercalated MgAl-hydrotalcites (β-CD-Ca/LDH) was synthesized to convert glycerol into high value-added glycerol carbonate(GC) by transesterification of dimethyl carbonate (DMC) and glycerol in this paper. β-cyclodextrin-metal complexes and β-CD-Ca/LDH was characterized by XRD, FT-IR, SEM, XPS and nitrogen adsorption-desorption. The enrichment of organic reactants in the hydrophobic cavity of β-cyclodextrin improved the collision probability of reactants. The intercalation of β-cyclodextrin-calcium complex (β-CD-Ca) increased the pore size and basic strength of catalyst. The experiment results showed that the glycerol conversion was 93.7% and the GC yield was 91.8% catalyzed by β-CD-Ca/LDH when the molar ratio of DMC and glycerol was 3:1, the catalyst dosage was 4 wt.%, the reaction temperature was 75 °C and the reaction time was 100 min while the glycerol conversion was 49.4% and the GC yield was 48.6% catalyzed by MgAl-LDH under the same conditions. [ABSTRACT FROM AUTHOR]

Ca-Mg-Al hydrotalcites were prepared by coprecipitation from Type S95 steel slag of Shanghai Baosteel Group as supports of ionic liquid in this paper. Five basic ionic liquids [Bmim][CH3COO], [Bmim][HCOO], [Bmim]OH, [Bmim]Br and ChOH were prepared and their catalytic performance on the synthesis of glycerol carbonate by transesterification between dimethyl carbonate and glycerol was investigated. The characterization results indicated that [Bmim]OH is the best ionic liquid (IL) for the transesterification reaction of glycerol carbonate. The hydrotalcites before and after intercalation by ionic liquid were characterized by XRD, FTIR, SEM, EDS and the IL were characterized by FT-IR, 13C-NMR and basicity determination via the Hammett method. The analysis results implied that the dispersion of [Bmim]OH in hydrotalcites reduced the alkali density appropriately and facilitated the generation of glycerol carbonate. The yield of glycerol carbonate and the conversion rate of glycerol reached 95.0% and 96.1%, respectively, when the molar ratio of dimethyl carbonate and glycerol was 3:1, the catalyst dosage was 3 wt%, the reaction temperature was 75 °C and the reaction time was 120 min. The layered structure of hydrotalcites increased the stability of ionic liquid intercalated in carriers, thus the glycerol conversion and the GC yield still remained 91.9% and 90.5% in the fifth reaction cycle. [ABSTRACT FROM AUTHOR]

Short-wavelength infrared (SWIR) light detection plays a key role in modern technologies. Emerging solution-processed organic semiconductors are promising for cost-effective, flexible, and large-area SWIR organic photodiodes (OPDs). However, the spectral responsivity ( R ) and specific detectivity ( D *) of SWIR OPDs are restricted by insufficient exciton dissociation and high noise current. In this work, we synthesized an SWIR small molecule with a spectral coverage of 0.3 to 1.3 micrometers peaking at 1100 nanometers. The photodiode, with optimized exciton dissociation, charge injection, and SWIR transmittance, achieves a record high R of 0.53 ampere per watt and D * of 1.71 × 10 13 Jones at 1110 nanometers under zero bias. The D * at 1 to 1.2 micrometers surpasses that of the uncooled commercial InGaAs photodiode. Furthermore, large-area semitransparent all-organic upconversion devices integrating the SWIR photodiode realized static and dynamic SWIR-to-visible imaging, along with excellent upconversion efficiency and spatial resolution. This work provides alternative insights for developing sensitive organic SWIR detection.

A novel angular-fused dithianaphthylquinone derivative, f-TX-TPA , was designed and selectively synthesized. The regioselectivity of angular-fused reaction was interpreted by theoretical calculations. The f-TX-TPA compound displayed excellent thermally activated delayed fluorescence property. Moreover, the organic light-emitting diodes (OLEDs) using f-TX-TPA as an emitter exhibited a high external quantum efficiency of 15.9%. These results indicated that angular-fused dithianaphthylquinone derivatives could have great potential in the application of high-efficiency OLEDs.

A series of thermally activated delayed fluorescence (TADF) exciplex based on the TX-TerPy were constructed. The electronic coupling between the triplet local excited states ( 3 LE) of the donors and acceptor and the charge transfer states had a great influence on the triplet exciton harvesting and Φ PL . Herein, based on this strategy, three donor molecules TAPC, TCTA, and m-MTDATA were selected. The local triplet excited state ( 3 LE) of the three donors are 2.93, 2.72 and 2.52 eV in pure films. And the 3 LE of TX-TerPy is 2.69 eV in polystyrene film. The energy gap between the singlet charge transfer ( 1 CT) states of TAPC:TX-TerPy (7:1), TCTA:TX-TerPy (7:1) and the 3 LE of TX-TerPy are 0.30 eV and 0.20 eV. Finally, the Φ PL of TAPC:TX-TerPy (7:1) and TCTA:TX-TerPy (7:1) are 65.2 and 69.6%. When we changed the doping concentration of the exciplex from 15% to 50%, the ratio of the triplet decreased, and Φ PL decreased by half, perhaps due to the increased energy gap between 1 CT and 3 LE. Therefore, optimizing the 1 CT, 3 CT, and 3 LE facilitated the efficient exciplex TADF molecules.