A novel kind of nanographene imide, namely pentaperylene decaimides (PPD) featuring dual‐core sixfold 5helicenes and ten imide groups, was efficiently obtained. Among the possible 28 stereoisomers, ...which include 14 pairs of enantiomers, only one pair of enantiomers was obtained selectively which could be separated by chiral HPLC. Single‐crystal X‐ray diffraction analyses revealed that it exhibits a D2‐symmetric “four‐bladed propeller” conformation composed of conjoined double “three‐bladed propeller”, which is very stable and could not convert into other conformations even when heated up to 200 °C. Meanwhile, enantiomerically pure PPD also exhibits an excellent resistance to thermally induced racemization, which makes it a promising candidate for various applications in chiral material science.
A kind of large nanographene imide featuring dual‐core arrangement of 5helicenes and imide groups has a D2‐symmetric “four‐bladed propeller” conformation which could not convert into other conformations even at 200 °C. The single chiral nanographene imide also exhibits excellent resistance to thermally induced racemization.
To address the issue of measurement errors in ultrasonic water meters caused by various interfering factors during the flow calibration process, this study proposes a highly automated and intelligent ...ultrasonic water meter flow calibration system design. Firstly, by analyzing and studying the working principle of the water flow calibration device, and considering the actual flow calibration range, the calibration method that combines the master meter method and the dynamic weighing method is determined. To enhance the automation level of the flow calibration system, the flow calibration control algorithm is thoroughly analyzed and designed. Finally, a flow correction algorithm based on linear interpolation was designed and utilized for water meter flow calibration. Test data show that after the flow correction, the value error of the ultrasonic water meter in the "high area" is not more than 2%, in the "low area" it is not more than 3%, and the repeatability is less than 0.05%. Compared with manual calibration, the flow calibration system designed in this paper enables high-precision automated flow calibration of ultrasonic water meters, significantly enhancing detection efficiency and accuracy.
High performance polypropylene/glass fiber (PP/GF) composites were prepared by introducing different percentage of maleic anhydride-g-polypropylene (MPP) and epoxy resin (EP) in the matrix. The ...coupling effect of MPP and EP on the mechanical properties of the hybrid composites were highlighted and the complicated reinforcing mechanism were discussed in detail. Even though the addition of MPP could apparently improve the performance of composites, as the EP coupled especially at higher MPP and EP content, both the tensile and impact strength get further enhancement. For the sample with 10 wt% MPP and 10 wt% EP (10MPP/10EP), the tensile and impact strength show significant enhancement by 136% and 171%, respectively, compared to the control PP/GF composite. It is demonstrated that the good compatibility among each constituent as well as the reaction between EP and MPP, which could efficiently facilitate the network formation, contribute to the high performance of the composites. The finer EP particles caused by the enhanced compatibility as nucleating agent could promote the crystallization, but the crystallinity of the composites does not change so much. A schematic mechanism of the interfacial structure on both molecular and microscopic levels is depicted, where the reaction between MPP and EP are considered as a dominated factor to influence the above-mentioned network formation. This local network structure causes the composites as an integrate showing excellent mechanical performance.
The China Energy Administration has issued policies to encourage energy storage to participate in the electric auxiliary service market, which will provide ideas for electric vehicle charging ...stations (EVCSs) to collectively participate in peak‐regulation and frequency modulation (FM). Taking into account the benefits of EVs participating in peak‐regulation and FM, this paper studies expansion planning for EVCSs. First, the orderly scheduling strategy of EVs under vehicle‐to‐grid (V2G) technology is established in this paper. And a peak regulation method is proposed to maximize the economic benefits of charging and discharging during peak and valley periods. Second, based on the temporal and spatial prediction model of EV charging demand, the expansion planning model of EVCSs is constructed considering the benefits of peak‐regulation and FM. Aiming at minimizing the comprehensive annual social cost of charging stations, the expansion site selection and capacity scheme of EVCSs are obtained. Finally, taking the 24 nodes in Xiangzhou District of Zhuhai City as an example, the location and capacity of the final annual expansion plan are obtained. And the influence of main control parameters on the results of the whole model and method is analysed in detail, the feasibility and effectiveness of the whole model and method are verified.
The reform of power spot market in China provides a new profit mode, determining energy trading strategy based on the power spot prices for distributed energy storages. However, individually ...accessing every distributed energy storage to the dispatch centre results in a high cost and low efficiency, which needs to be improved by connecting through the aggregator. To this end, this paper proposes a regulation mode and strategy for distributed energy storages participating in energy trading through aggregation. First, the optimal centres of distributed energy storages are searched as the aggregation centres according to the electrical distance distributed by the energy storage, and the model of each distributed energy storage aggregation group is established. On this basis, the conditional value at risk (CVaR) method is introduced to quantify the income risk brought by the fluctuation of power spot prices, following with the optimization model for day‐ahead stage and real‐time stage. Finally, case studies under multiple scenarios of power spot market verify that the regulation mode and strategy can effectively guarantee the economic profits of distributed energy storages by setting aggregation groups and reasonable risk preference coefficients.
Organic phosphorescence, originating from triplet excitons, has potential for the development of new generation of organic optoelectronic materials. Herein, two heavy‐atom‐free room‐temperature ...phosphorescent (RTP) electron acceptors with inherent long lifetime triplet exctions are first reported. These two 3D‐fully conjugated rigid perylene imide (PDI) multimers, as the best nonfullerene wide‐bandgap electron acceptors, exhibit a significantly elevated T1 of ≈2.1 eV with a room‐temperature phosphorescent emission (τ = 66 µs) and a minimized singlet–triplet splitting as low as ≈0.13 eV. The huge spatial congestion between adjacent PDI skeleton endows them with significantly modified electronic characteristics of S1 and T1. This feature, plus with the fully‐conjugated rigid molecular configuration, balances the intersystem crossing rate and fluorescence/phosphorescence rates, and therefore, elevating ET1 to ≈2.1 from 1.2 eV for PDI monomer. Meanwhile, the highly delocalized feature enables the triplet charge‐transfer excitons at donor–acceptor interface effectively dissociate into free charges, endowing the RTP electron acceptor based organic solar cells (OSCs) with a high internal quantum efficiency of 84% and excellent charge collection capability of 94%. This study introduces an alternative strategy for designing PDI derivatives with high‐triplet state‐energy and provides revelatory insights into the fundamental electronic characteristics, photophysical mechanism, and photo‐to‐current generation pathway.
The long‐lived excitons are of significance to alleviate the strong morphology‐ and thickness‐dependence of organic photovoltaic performance and therefore accelerating its industrialization process. Here, two room‐temperature phosphorescent electron acceptors with long‐lived triplet exctions and high‐energy level are investigated systematically for the first time. This work provides revelatory insights into their fundamental electronic characteristics, photophysical mechanism, and photo‐to‐current generation pathway.
Despite the great progress in research on molecular carbons containing multiple helicenes around one core, realizing the stereoselectivity of carbons containing multiple helicenes around more cores ...is still a great challenge. Herein, molecular carbon C204 featuring 12‐fold 5helicenes around four cores was successfully constructed by using nine perylene diimide (PDI) units, and exhibits good solubility and stability. Despite 256 possible stereoisomers caused by the 12‐fold 5helicenes, we only obtained one pair of enantiomers with D3 symmetry. There are four possible pairs of enantiomers with D3 symmetry, namely 7A, 7B, 7C and 7D. Theoretical and experimental results verify that the obtained structure belongs to 7C, which has the lowest energy. The enantiomers can also be separated by chiral HPLC. These results suggest that choosing PDIs as building blocks can not only improve the solubility and stability but also realize the stereoselectivity and chirality of molecular carbons.
A molecular carbon imide featuring 12‐fold 5helicenes around four cores has been constructed using perylene diimide units. The structure exhibits high stereoselectivity and chirality, good solubility, and stability. Although there are four possible pairs of enantiomers with D3 symmetry, the results verify that the obtained structure belongs to the one having the lowest energy. The enantiomers can also be separated by HPLC on a chiral stationary phase.
Very recently, the experimental synthesis of biphenylene network (BPN) monolayer has achieve a great progress (Matetskiy et al., 2021). However, a systematic study of the potential devices based on ...the BPN monolayer is still lacking up to date. In this paper, several conceptual BPN-based nanodevices are proposed and their electronic transport properties are revealed by using the density functional theory combined with non-equilibrium Green’s function method. First, the pristine BPN-based devices exhibit obvious electronic transport anisotropy along the zigzag and armchair directions. Moreover, a significant negative differential resistance (NDR) effect along the armchair direction is observed as well. Second, the gas sensitivities of the BPN-based gas sensor to NO and NO2 along the armchair direction are as high as 1.63 and 2.75, respectively. Finally, the BPN monolayer undergoes a metal–semiconductor transition in the case of N13 or N14 doping strategy. Therefore, Schottky junction device formed by the pristine and N14 doped BPN monolayer is constructed and its maximum rectification ratio reaches ∼104 at low bias voltage. These results demonstrate that the BPN monolayer is a multifunctional material and may find various potential applications in electronic anisotropy, NDR, gas sensor, and even Schottky junction devices.
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•Anisotropic transport and NDR effects were found in the pristine BPN monolayer.•Sensitivities of the BPN to NO and NO2 are as high as 1.63 and 2.75, respectively.•The maximum rectification ratio of the BPN-based Schottky junction reaches 104.•2D multifunctional BPN-based nanodevices were proposed.
1D nonplanar graphene nanoribbons generally have three possible conformers: helical, zigzag, and mixed conformations. Now, a kind of 1D nonplanar graphene nanoribbon, namely dodecatwistarene imides ...featuring twelve linearly fused benzene rings, was obtained by bottom‐up synthesis of palladium‐catalyzed Stille coupling and C−H activation. Single‐crystal X‐ray diffraction analyses revealed that it displays a zigzag‐twisted conformation caused by steric hindrance between imide groups and neighboring annulated benzene rings with the pendulum angle of 53°. This conformation is very stable and could not convert into other conformations even when heated up to 250 °C for 6 h. Despite of the highly twisted topology, organic field‐effect transistor based on it exhibits electron mobility up to 1.5 cm2 V−1 s−1 after annealing.
1D nonplanar graphene nanoribbon, namely dodecatwistarene imide featuring twelve linearly fused benzene rings, was obtained by Pd‐catalyzed Stille coupling and C−H activation. It has a zigzag‐twisted conformation with the pendulum angle of 53°, and is very stable even when heated up to 250 °C. An organic field‐effect transistor based on it exhibits electron mobility up to 1.5 cm2 V−1 s−1.
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