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A new inverse synthetic aperture radar (ISAR) imaging framework is proposed to obtain high cross-range resolution under sparse aperture conditions, which is a challenge when the signal-to-noise ratio is low. Motivated by the sparsity and low rank of target’s 2-D distribution, the imaging problem is converted to the simultaneously sparse and low-rank signal matrix reconstruction problem under multiple measurement vector (MMV) model, and a novel reconstruction method based on joint constraints of sparsity and low rank is proposed. Due to the over-relax problem, the traditional convex optimization method cannot achieve a better performance using joint structures than exploiting just one of the constraints. As such, a nonconvex penalty function is introduced. To avoid the local minima, the convexity of the cost function should be ensured when constructing the nonconvex penalty function. The adaptive filtering framework, which is a powerful way to recovery the sparse low-rank matrix accurately from its noisy observation, is adopted as a reconstruction algorithm. Furthermore, the optimal step size formula and the idea of smoothed zero norm are used to enhance the convergence and the ability to suppress noise. The newly proposed method is verified by the simulation experiment, which has a better performance in image quality, robustness to noise, and imaging speed.

The nucleation and growth mechanism and polymorph-property correlations in the molecular cocrystal field are widely sought but currently remain unclear. Herein, a new wire-like morphology of phenazine ( Phz )-chloranilic acid ( H2ca) cocrystal (PHC) is demonstrated for the first time, and the self-assembly of Phz and H2ca is controlled to selectively prepare kinetically stable wires and thermodynamically stable plates. Specifically, low precursor concentration is beneficial for one-dimensional (1D) self-assembly along the [010] crystallographic direction, while only supersaturation can trigger 2D self-assembly along the [100] and [010] directions, respectively. This is understandable in terms of the (020) face showing the largest attachment energy ( E att) and the (002) face possessing the smallest surface energy ( E surf). Moreover, anisotropic Raman spectra related to the mode symmetry and atomic displacements in two types of PHCs are revealed, and the same Raman-active vibrational bands of PHC wire and plate show different polarization responses, which is intrinsically ascribed to their different molecular orientations. Overall, this is the first case that morphologies of cocrystal are precisely tuned with comprehensive investigations of their anisotropic vibrational characteristics.

With the development of depth learning and synthetic aperture radar (Synthetic Aperture Radar, SAR) technology, SAR image target detection based on convolution neural network (convolutional neural network, CNN) has achieved certain results. However, there are still problems in SAR detection of near-shore ship targets in complex environments. For improving the detection performance of the algorithm, the detection rate of SAR image near shore ship targets in complex environment is improved. This paper proposes an algorithm for SAR image ship target detection in complex environment. The algorithm first uses convolution neural network for coastal segmentation, and SAR image ship target detection through the results of coastal segmentation. The experimental results show that the algorithm has efficient detection ability for SAR image near-shore ship target detection in complex environment.

To deal with the problem of de-noising and enhancement of radar signal time-frequency images, a method of secondary generating time-frequency images by generative adversarial network is proposed. Firstly, time-frequency analysis is used to generate the time-frequency image of the radar signal as the original data set 1. Then, after learning the data set 1 by using the generative adversarial network, a new data set 2 is generated, and the data set 2 has de-noising and enhancement effects relative to data set 1. Finally, the validity of the data set 2 generated by the time-frequency image singular value feature is checked. Experiments on the time-frequency images of five common radar signals are carried out. The results show that the method is effective in time-frequency image de-noising and increasing sample diversity.

Bistatic inverse synthetic aperture radar (ISAR) can increase the probability of tracking the high-speed target and provide more angle information than monostatic ISAR. However, bistatic ISAR suffers from a serious defocusing problem, resulting from the high-speed motion. Furthermore, the inherent geometry distortion and calibration problems make bistatic ISAR (B-ISAR) imaging more complex. In response to these problems, we propose a bistatic ISAR imaging method for high-speed moving target with geometric distortion correction and calibration based on dechirping processing. At first, based on the motion decomposition idea, the B-ISAR echo model of the high-speed moving target is established. Then, by analyzing the imaging mechanism of the Range-Doppler algorithm (RDA), we eliminate the phase items influencing the imaging quality with speed compensation and Doppler compensation. After that, the analytic formula of the geometric distortion factor and calibration factor are deduced, which helps transform the geometric correction and calibration problem into a parameter estimation problem. Finally, with the sparsity of the scattering points, the required parameters are solved using the expectation maximization (EM) algorithm based on the maximum a posteriori probability criterion. With the estimated parameters, a clear B-ISAR image of a high-speed moving target with geometric correction and calibration is obtained. The simulations show that the proposed method has a better resolution and simultaneously attains geometric correction and calibration of the image.

Simultaneously modulating the optical and electrical properties of organic semiconductors is crucial for advancing their desired applications in integrated optoelectronic devices. Here, we realize a goal of optimizing the light emission and field-effect properties of an anthracene derivative, 1,4-di(anthracen-9-yl)buta-1,3-diyne (DABD) by tuning its crystal polymorphs. Two phase crystals, that is α-phase rhombic-sheet crystals and β-phase ribbon-shape crystals of DABD are controllably obtained. Compared with the α-phase crystals, the β-phase DABD crystals exhibit better integrated optoelectronic performances with charge carrier mobility of 0.25 cm2 V−1 s−1 and strong fluorescent emission. This work suggests that polymorph engineering would be a promising avenue to realize simultaneous modulation of the multifunctional properties of organic semiconductors towards appropriate applications in organic optoelectronics.

We show here that breath figure–derived semiconducting films are suitable and universal for porous organic electronics., Porous semiconductor film morphologies facilitate fluid diffusion and mass transport into the charge-carrying layers of diverse electronic devices. Here, we report the nature-inspired fabrication of several porous organic semiconductor-insulator blend films [semiconductor: P3HT (p-type polymer), C8BTBT (p-type small-molecule), and N2200 (n-type polymer); insulator: PS] by a breath figure patterning method and their broad and general applicability in organic thin-film transistors (OTFTs), gas sensors, organic electrochemical transistors (OECTs), and chemically doped conducting films. Detailed morphological analysis of these films demonstrates formation of textured layers with uniform nanopores reaching the bottom substrate with an unchanged solid-state packing structure. Device data gathered with both porous and dense control semiconductor films demonstrate that the former films are efficient TFT semiconductors but with added advantage of enhanced sensitivity to gases (e.g., 48.2%/ppm for NO2 using P3HT/PS), faster switching speeds (4.7 s for P3HT/PS OECTs), and more efficient molecular doping (conductivity, 0.13 S/m for N2200/PS).

A cocrystal strategy with a simple preparation process is developed to prepare novel materials for near-infrared photothermal (PT) conversion and imaging. DBTTF and TCNB are selected as electron donor (D) and electron acceptor (A) to self-assemble into new cocrystals through non-covalent interactions. The strong D-A interaction leads to a narrow band gap with NIR absorption and that both the ground state and lowest-lying excited state are charge transfer states. Under the NIR laser illumination, the temperature of the cocrystal sharply increases in a short time with high PT conversion efficiency (η=18.8 %), which is due to the active non-radiative pathways and inhibition of radiative transition process, as revealed by femtosecond transient absorption spectroscopy. This is the first PT conversion cocrystal, which not only provides insights for the development of novel PT materials, but also paves the way of designing functional materials with appealing applications.

A sensitive, and single step reaction assay of glycoproteins in antibody-free mode was proposed on a 4-mercapto-phenylboronic acid (4-MPBA) modified silver nanoparticle film (AgNF) by using surface enhanced Raman scattering (SERS). 4-MPBA/AgNF was designed both as a glycoprotein-specific recognition biosensor and as a Raman reporter for the SERS platform. Variation in the ratio I1574/I1586 for 4-MPBA/AgNF in response to glycoprotein capture constitutes the SERS assay which exhibits high sensitivity and selectivity against nonglycoproteins and is shown to function in complex samples.

Cocrystals of 4-styrylpyridine and 1,2,4,5-tetracyanobenzene were successfully prepared by supramolecular self-assembly. Donor-acceptor interactions between the molecular components are the main driving force for self-assembly and contribute to intermolecular charge transfer. The cocrystals possess two-photon absorption properties that are not observed in the individual components; suggesting that two-photon absorption originates from intermolecular charge-transfer interactions in the donor-acceptor system. The origin of two-photon absorption in multichromophore systems remains under-researched; thus, the system offers a rare demonstration of two-photon absorption by cocrystallization. Cocrystal engineering may facilitate further design and development of novel materials for nonlinear optical and optoelectronic applications.

We investigate backbone fluorination effects in bulk-heterojunction (BHJ) polymer solar cells (PSCs) with the fluorine-poor PBDTT-FTTE and fluorine-rich PBDTTF-FTTE donor polymers, paired with the ...

Aiming at the problem that the existing radar emitter identification method cannot effectively identify the radar signal unknown to the prior knowledge base, this paper introduces the joint distribution adaptation algorithm in transfer learning into the field and adds data label to the algorithm optimization item. And a radar emitter identification method based on discriminant joint distribution adaptation is proposed. The method firstly maps different radar signal data to the same hidden space by using the discriminant joint distribution adaptation algorithm to reduce the distribution discrepancy between the radar signal known by the prior knowledge base and the radar signal unknown to the prior knowledge base. Then the support vector machine is trained by using the radar signal data with known tags in the hidden space, and the trained model is used to identify the radar signal. Simulation experiments show that the proposed method can effectively improve the recognition of radar signals unknown to the prior knowledge base.

To solve the problem of the low rate of template matching (TM) jamming decision method under the incomplete jamming rule library condition in traditional electronic warfare, a clustering and resampling – support vector machine (CRS-SVM) jamming decision method, is proposed. For the air-to-air scene of airborne multifunctional fire control radar, the inter-pulse pulse and intra-pulse features are extracted, and a jamming rule library that is divided into the source domain and target domain sample according to the missing rate is constructed in this scene. DBSCAN algorithm is used to cluster the dataset, and the structure information is found. The training samples are generated via resampling. SVM is used to transform the inner product of the target domain space into the inner product of the feature space to establish the feature space hyperplane. The target domain samples are labelled as the corresponding jamming style label to realise the fast and effective decision. The experiment results show that the proposed method can effectively improve the accuracy and robustness of jamming decision compared with the traditional TM method.

Aiming at the problem that traditional decision-making system of jamming is difficult to apply to modern warfare due to the rapid development of multifunctional radar and cognitive electronic warfare, a decision-making system of cognitive jamming against multifunctional radar is studied. Firstly, the paper takes multifunctional radar as the combat object, and analyses its working mode under search mode and tracking mode and their transformation, which provides theoretical basis and foundations for the research of decision-making system of cognitive jamming. Secondly, the shortcomings of traditional decision-making system of jamming are analyzed. Combined with cognitive thought, the decision-making system of cognitive jamming is proposed. Subsequently, the construction and update of jamming case library in the system is introduced. Finally, the basic principles of reinforcement learning and deep reinforcement learning and their applications in decision-making system of cognitive jamming are analyzed.

Cocrystal polymorphs based on sym-triiodo-trifluorobenzene (IFB) with 1,4-di(4′-pyridyl)-1,3-diacetylene (DPDA) are formed with halogen bond interactions. Two cocrystal phases were obtained by using different solvents, acetonitrile and methylene chloride, and confirmed by their single crystal structure data. In the application direction, the different photo-physical properties of the two phases were discussed carefully.

It is a common phenomenon for organic semiconductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molecular crystal polymorphs (i.e., adjusting the same molecule with different packing arrangements in solid state) towards efficient charge transport and high performance devices. Here, the choice of solvent had a marked effect on controlling the growth of α-phase ribbon and β-phase platelet during crystallization for an indenofluorene (IF) π-extended tetrathiafulvalene (TTF)-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the α-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic semiconductors.

The spectroscopic and photophysical properties of organic materials in the solid-state are widely accepted as a result of their molecular packing structure and intermolecular interactions, such as J- and H-aggregation, charge-transfer (CT), excimer and exciplex. However, in this work, we show that Spe-F4DIB cocrystals (SFCs) surprisingly retain the energy levels of photoluminescence (PL) states of Spe crystals, despite a significantly altered molecular packing structure after cocrystallization. In comparison, Npe-F4DIB cocrystals (NFCs) with new spectroscopic states display different spectra and photophysical behaviors as compared with those of individual component crystals. These may be related to the molecular configuration in crystals, and we propose Spe as an “intramolecular emissive” material, thus providing a new viewpoint on light-emitting species of organic chromophores. Moreover, the nonlinear optical (NLO) properties of Npe and Spe are firstly demonstrated and modulated by cocrystallization. The established “molecule-packing-property” relationship helps to rationally control the optical properties of organic materials through cocrystallization.

The integrated vertical-flow constructed wetland (IVCW) is considered as a potential alternative for domestic wastewater treatment of towns and small cities. Oxygen supply is the main limitation of pollutants removal in IVCWs. In the present study, a field experiment was conducted to evaluate the capacity and kinetics of pollutants removal in IVCWs with/without artificial aeration. Two IVCWs constructed with Canna indica and Phragmites australis were running in continuous flow to remove high concentrations of conventional pollutants and low concentrations of tetracyclines (TETs), which are at similar levels of domestic wastewater. The results showed that IVCWs had a good performance on COD, phosphorus, and TETs with removal efficiencies over 80%, 64%, and 75%, respectively, with a hydraulic retention time (HRT) of 3.0 d. However, the removal of nitrogen was limited, showing as TN removal efficiency of about 30%. The IVCW with Phragmites australis had a higher removal efficiency and rate. A kinetics based on Monod Equation and solved with Matlab 2018a could describe the degradation of conventional pollutants. Artificial aeration improved the oxygen supply and remarkably raised the removal capacity for COD, N, and P in IVCWs. The q1/2 values, which was defined as the average removal loading before half of the pollutants was removed and represented the removal capacity without limitation of pollutants concentration, were increased by 5–30 times after aeration. In conclusion, IVCWs could remove conventional pollutants and TETs simultaneously showing a great potential in domestic wastewater treatment. Artificial aeration enhanced removal capacity of IVCWs on conventional pollutants while showed little influence on TETs.

Organic semiconductor-insulator blend films are widely explored for high-performance electronic devices enabled by unique phase-separation and self-assembly phenomena at key device interfaces. Here we report the first demonstration of high-performance hybrid diodes based on p- n junctions formed by a p-type poly(3-hexylthiophene) (P3HT)-poly(methyl methacrylate) (PMMA) blend and n-type indium-gallium-zinc oxide (IGZO). The thin film morphology, microstructure, and vertical phase-separation behavior of the P3HT films with varying contents of PMMA are systematically analyzed. Microstructural and charge transport evaluation indicates that the polymer insulator component positively impacts the morphology, molecular orientation, and effective conjugation length of the P3HT films, thereby enhancing the heterojunction performance. Furthermore, the data suggest that PMMA phase segregation creates a continuous nanoscopic interlayer between the P3HT and IGZO layers, playing an important role in enhancing diode performance. Thus, the diode based on an optimal P3HT-PMMA blend exhibits a remarkable 10-fold increase in forward current versus that of a neat P3HT diode, yielding an ideality factor value as low as 2.5, and a moderate effective barrier height with an excellent rectification ratio. These results offer a new approach to simplified manufacturing of low-cost, large-area hybrid inorganic-organic electronics technologies.

The existing NBI parameter estimation algorithms for DSSS communications are confined to the high sampling rate. In order to solve the problem above, the compressive sensing (CS)is applied to the NBI parameter estimation in DSSS communications. A partial reconstruction algorithm is proposed to get the NBI feature vector from the compressed signal using the different feature of DSSS signal and NBI in compressed domain and the block sparsity feature of NBI in frequency domain. Besides, an edge location estimation method is proposed to realize the NBI parameter estimation by estimating the edge of the transformed feature vector. We will achieve the NBI bandwidth estimation after we get the edge location. Reported simulation results demonstrate that the proposed methods are effective to the NBI parameter estimation in DSSS communications. The performance is mainly affected by the variety of interference intensity and compression rate. Under the condition of same interference bandwidth, the larger the interference intensity is and the greater the compression rate is, the better the interference parameter estimation performance is.

We report the results of a study to enhance metal oxide (MO) thin-film transistor (TFT) performance by doping both the semiconductor (In2O3) and gate dielectric (Al2O3) layers with boron (yielding IBO and ABO, respectively) and provide the first quantitative analysis of how B doping affects charge transport in these MO dielectric and semiconducting matrices. The impact of 1–9 atom % B doping on MO microstructure, morphology, oxygen defects, charge transport, and dielectric properties is analyzed together, in detail, by complementary experimental (microstructural, electrical) and theoretical (ab initio MD, DFT) methods. The results indicate that B doping frustrates In2O3 crystallization while suppressing defects responsible for electron trapping and carrier generation. In the adjacent Al2O3 dielectric, B doping increases the dielectric constant and refractive index while reducing leakage currents. Furthermore, optimized solution-processed TFTs combining IBO channels with 6 atom % B and ABO dielectrics with...

New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π−π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.

To solve the low accuracy problem of the template matching(TM) method under condition of feature incomplete database in traditional EW, a multiple division support vector machine (MD-SVM) jamming decision method is proposed. For the air-to-air scene airborne multi-functional fire control radar, a feature incomplete database is constructed. The sample set is divided into multiple sample subsets using multiple division method. The inner product of multiple sample subset spaces is transformed to the inner product of the feature space by SVM. Feature space hyperplane is established, and the jamming tags corresponding to the sample subsets are output. Then the jamming style is quickly and effectively determined. The experimental results show that the proposed method can effectively improve the accuracy and robustness of the jamming decision compared with the traditional TM and non-multiple division method. The feature incomplete database jamming decision problem is solved for its excellent learning and generalization ability.

A challenge in frequency hopping spread spectrum (FHSS) communication chirp interference mitigation is the requirement of a high sampling rate for wideband FHSS signal. We demonstrate that we could filter out the interference in the system after compressed sampling. Using different sparsity feature of the FHSS signal and the chirp interference, a chirp interference mitigation model is proposed in this paper, we achieve the interference mitigation by suppressing the interference components in the signal sparse coefficient vector which is estimated using the compressed data. The algorithm is designed using two stage compressive sampling matching pursuit (CoSaMP) algorithm. In contrast with traditional methods, the proposed method could suppress the chirp interference effectively with the prior information of the interference sparse degree. The simulation results show a reliable chirp interference mitigation performance even in low SNR and low sub- sampling rate, the interference mitigation performance is robust to the variations of the interference intensity and the interference cycle.

With the rapid development of organic electronics, one-dimensional (1D) organic p–n heterojunctions have attracted increasing interest because of their unique optoelectronic properties and potential as building blocks for sophisticated integrated circuits. Recently, significant progress has been made in the methods for synthesizing or fabricating 1D organic p–n heterojunctions, including two typical types of organic–organic heterojunctions and organic–inorganic heterojunctions. Various device applications have been demonstrated based on these 1D organic heterojunctions with new or enhanced optical and/or electrical properties. This MiniRev highlights the recent remarkable advances in this field with a concise summary of the various preparation methods such as solution process, physical vapor techniques, template and templateless methods, etc., to form segmented, cross-stacked, bilayer, and core–shelled structures. The potential applications of these 1D organic heterojunctions in optoelectronic devices, such as ambipolar transistors, photovoltaics, photodetectors and diodes, are demonstrated in the second part. Finally, the challenges and potential opportunities existing in this field are also deeply discussed.

We report here a systematic study of the solid-state packing, optoelectronic properties and organic field-effect transistor properties of three isomeric 2,6-di-pyridyl anthracene derivatives (1a, 1b and 1c). Very different solid-state physicochemical behaviours were found as a result of the subtle change in the substitution site, especially in the solid-state emission and charge transport properties. For 1a and 1b, which adopted H-like aggregates in the solid state, a bright blue emission with fluorescent quantum efficiencies (ΦF) of 50.2 and 17.5% and thin film mobilities of 0.05 and 10−5 cm2 V−1 s−1, respectively, were obtained. The inferior mobility of 1b might be caused by the larger torsion and herringbone angle in the solid-state packing. A green emission with ΦF of 16% was obtained for single crystals of 1c. No charge transport property was observed for 1c, which might be related to the unfavourable solid-state packing and poor film morphology.

Radar emitter identification based on machine learning technology at present mostly assumes that the test set is identically distributed with and the training set, which causes the classification effect is not well when the database samples and the true distribution of the signals are biased. Thus, the theory of transfer learning is introduced into the identification system, and a radar emitter signal identification method based on structural discovery and re-balancing is proposed. By means of database data and target data clustering analysis and re-sampling, correct the distribution and put the new data to the Support Vector Machine (SVM) for training and identifying reconnaissance samples. The simulation results show that the classification performance of the Support Vector Machine model in the new training sample set has been greatly improved.

Organic cocrystals, formed by a combination of electron-rich donors and electron-poor acceptors, play an important role in tailoring the optoelectronic properties of molecular materials. Charge transfer interactions in cocrystals not only endow them with an ordered three-dimensional (3D) supramolecular network in different constituent units, but also render them ideal scaffolds to control the intermolecular interactions in multicomponent solids. In this perspective, we firstly introduce preparation methods, molecular packing modes and charge transfer in organic cocrystals. Then, we focus on the novel and promising optoelectronic properties of organic cocrystals based on charge transfer interactions. Finally, we briefly discuss the outlook for the future development of these multicomponent crystalline materials.

In view of the problem that support vector machine classifier learning new knowledge is poor in real time, a new algorithm of radar emitter identification based on hull vector and Parzen window density estimation is studied. The algorithm takes the Parzen window density estimation to eliminate the outliers, and reduces the training time by using the hull vector of the sample set. The identification of radar signal samples is finished by using the trained classifier. The simulation results show that the online learning algorithm based on hull vector and Parzen window density estimation has good timeliness and high recognition rate.

Organic cocrystals that are composed of two or more components usually exhibit novel, unpredictable, and even unique properties rather than a simple combination of the properties of their components, such as white-light emission, ambipolar charge transport, nonlinear optics, and ferroelectricity. Since cocrystal engineering represents a novel strategy for synthesizing multifunctional materials, which opens the door for molecular collaborative innovation, it has aroused much attention in recent years. However, as it is also a relatively new research field, it is only in its early stages of development. In order to provide readers with an understanding of the future design of cocrystals for potential applications, a brief review of organic cocrystals is presented here, including an introduction to organic cocrystals as well as discussions of cocrystal preparation, methods and techniques of characterization, and multifunctional applications of cocrystals. Moreover, the outlook for further studies and applications of cocrystal engineering is considered.

In this study, 1D nanocrystals composed of C60 and corannulene were synthesized efficiently through cocrystallization by a solution process. These 1D nanocrystals display high electron transport characteristics of up to 0.11 cm(2) V(-1) s(-1) and good photoresponse of 0.09 A W(-1), indicating their potential applications in optoelectronics. The results suggest that co-crystal engineering provides a novel strategy for the rational design of new carbon-based crystalline nanomaterials.

Vertically aligned nanowires (NWs) of single crystal semiconductors have attracted a great deal of interest in the past few years. They have strong potential to be used in device structures with high density and with intriguing optoelectronic properties. However, fabricating such nanowire structures using organic semiconducting materials remains technically challenging. Here we report a simple procedure for the synthesis of crystalline 9,10-bis(phenylethynyl) anthracene (BPEA) NWs on a graphene surface utilizing a solution-phase van der Waals (vdW) epitaxial strategy. The wires are found to grow preferentially in a vertical direction on the surface of graphene. Structural characterization and first-principles ab initio simulations were performed to investigate the epitaxial growth and the molecular orientation of the BPEA molecules on graphene was studied, revealing the role of interactions at the graphene-BPEA interface in determining the molecular orientation. These free-standing NWs showed not only efficient optical waveguiding with low loss along the NW but also confinement of light between the two end facets of the NW forming a microcavity Fabry-Pérot resonator. From an analysis of the optical dispersion within such NW microcavities, we observed strong slowing of the waveguided light with a group velocity reduced to one-tenth the speed of light. Applications of the vertical single-crystalline organic NWs grown on graphene will benefit from a combination of the unique electronic properties and flexibility of graphene and the tunable optical and electronic properties of organic NWs. Therefore, these vertical organic NW arrays on graphene offer the potential for realizing future on-chip light sources.

Bistatic inverse synthetic aperture radar (ISAR) can help image the high-speed target for its advantage in tracking and more observation angle to provide more information than monostatic ISAR. However, the complex image geometry makes it difficult to achieve a clear image of the target with geometry distortion correction and calibration. Furthermore, high-speed motion will make the image blurred or defocussed. To address these problems, a bistatic ISAR (B-ISAR) imaging method for high-speed motion target with geometric distortion correction and calibration is proposed. According to the motion decomposition idea, we established the B-ISAR echo model of the high-speed motion target. Then, based on the range Doppler algorithm, we deduce the analytic formula of the geometric distortion factor and calibration factor, and transform the imaging problem into a parameter estimation problem. With the sparsity of the scattering points, the required parameters are solved using the expectation maximization algorithm based on the maximum a posteriori probability criterion. With the estimated parameters, a clear B-ISAR image of a high-speed motion target with geometric correction and calibration is obtained. The simulations show that the proposed method has better resolution and simultaneously attains geometric distortion correction and calibration of the image.

The charge transfer and photophysics in a new light-emitting cocrystal with ribbon-like morphology are revealed in-depth. These cocrystals can serve as an efficient 1D optical waveguide, and the cocrystal waveguide couplers fabricated by a probe-assisted crystal-moving technique exhibit interfacial white emission and can function as basic photonic logic gates, showing potential for future integrated photonics.