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The increase of atmospheric CO2 concentration has caused many environmental issues. Electrochemical CO2 reduction reaction (CO2RR) has been considered as a promising strategy to mitigate these challenges. The electrocatalysts with a low overpotential, high Faradaic efficiency, and excellent selectivity are of great significance for the CO2RR. Carbon-based materials including metal-free carbon catalysts and metal-based carbon catalysts have shown great potential in the CO2RR, owing to the tailorable porous structures, abundant natural resources, resistance to acids and bases, high-temperature stability, and environmental friendliness. In this review, various carbon materials including graphene, carbon nanotubes, quantum dots, porous carbon, and MOF-derived catalysts, etc., for the CO2RR have been summarized. Particularly, recent progress in terms of the mechanism and pathway of CO2 conversion has been comprehensively reviewed. Finally, the opportunities and challenges of carbon-based electrocatalysts for the CO2RR are proposed.

The design of two-photon absorption (TPA) materials based on cocrystal engineering is an emerging strategy for constructing nonlinear materials. Here we observe that a prepared BDBT-TCNB cocrystal can retain well the TPA properties from the donor BDBT molecules, but the TPA properties of a BDBT-OFN cocrystal are inhibited upon using the same donor molecule but changing the acceptor molecule of the cocrystal. Via comparing the crystal structures and spectral data of the two cocrystals, we find that BDBT-TCNB cocrystals have obvious intermolecular charge transfer interactions, while the BDBT-OFN cocrystals exhibit totally different intermolecular arene–perfluoroarene interactions. Moreover, strong charge transfer interactions involving the BDBT-TCNB cocrystal also promote an enhancement of the fluorescence intensity and an increase in the lifetime and photoluminescence quantum yield (PLQY) relative to the monomers. Therefore, this example proves that intermolecular interactions involving cocrystals can be controlled via carefully selecting the donor and acceptor molecules, and then the TPA properties of the cocrystals can be selectively adjusted, promoting the development of TPA materials prepared via cocrystal engineering.

Two-dimensional (2D) crystals of conjugated polymers (2DCCPs) have attracted significant attention in the past few decades due to their superior and intriguing optoelectronic properties. With the increase in brain-inspired neuromorphic computing, 2DCCPs have also been employed in the construction of synaptic devices because they offer clear advantages of easy integration, high stability, long–range order and no biological rejection. However, pursuing controllable strategies to obtain high-quality and large-scale 2DCCPs remains a challenge on account of their intrinsic complex structures. Herein, we present a universal methodology to grow centimeter-scale 2DCCPs in a controlled manner within minutes by selecting an appropriate growth-assisting solvent and surfactant. The thickness of the as-produced 2DCCPs was down to two molecular layers. The photonic synaptic transistors based on the as-grown 2DCCPs could perform typical synaptic functions, including short-term plasticity, paired-pulse facilitation, long-term plasticity and spike intensity-dependent plasticity. The transistor was also proven to have potential application as a high-pass filter. This methodology shows great potential to be expanded to many other polymer systems and opens new pathways for large-area integrated wireless communication systems and artificial visual systems.

Series tunneling across peptides composed of various amino acids is one of the main charge transport mechanisms for realizing the function of protein. Histidine, more frequently found in redox active proteins, has been proved to be efficient tunneling mediator. While how it exactly modulates charge transport in a long peptide sequence remains poorly explored. In this work, we studied charge transport of a model peptide junction, where oligo-alanine peptide was doped by histidine at different position, and the series of peptides were self-assembled into a monolayer on gold electrode with soft EGaIn as top electrode to form molecular junction. It was found that histidine increased the overall conductance of the peptide, meanwhile, its position modulated the conductance as well. Quantitative analysis by transport model and ultraviolet photoelectron spectroscopy (UPS) indicated a sequence dependent energy landscape of the tunneling barrier of the junction. Density-functional theory (DFT) calculation on the electronic structure of histidine doped oligo-alanine peptides revealed localized highest occupied molecular orbital (HOMO) on imidazole group of the histidine, which decreased charge transport barrier.

Organic cocrystal engineering refers to two or more organic molecules stoichiometrically combined and held together by noncovalent intermolecular interactions, which differs from standard chemical synthesis involving covalent bond breakage and formation. Organic cocrystals have unique properties and offer a new strategy for creating enhanced organics. First, however, some key questions need to be addressed: How do diverse monomers affect the intermolecular interaction kinetics during cocrystallization? How do the intermolecular forces in cocrystals affect cocrystal functions? In this Perspective, the definition and advantages of organic cocrystal engineering, specifically in the construction of a reliable intermolecular interaction-stacking structure-performance relationship, are outlined. Additionally, recent developments in the field and the questions above are discussed. Finally, a brief conclusion and some hints on likely future developments are provided.

Organic electrode materials have exhibited good electrochemical performance in batteries, but their voltages and rate capabilities still require improvement to meet the increasing demand for batteries with high energy and power density. Herein, we design and synthesize a branched dihydrophenazine-based polymer (p-TPPZ) as a cathode material for dual-ion batteries (DIBs) through delicate molecular design. Compared with the linear dihydrophenazine-based polymer (p-DPPZ, with a theoretical capacity of 209 mAh g–1), p-TPPZ possessed a higher theoretical capacity of 233 mAh g–1 and lower highest occupied molecular orbital energy levels, which resulted in a high actual capacity (169.3 mAh g–1 at 0.5 C), an average discharge voltage of 3.65 V (vs. Li+/Li) and a high energy density (618.2 Wh kg–1, based on the cathode materials). The branched structure of p-TPPZ led to a larger specific surface area than that of p-DPPZ, which was beneficial for the electrolyte infiltration and fast ionic transport, contributing to the high power density. Due to the fast reaction kinetics, even at a power density of 23, 725 W kg–1 (40 C), the energy density still reached 474.5 Wh kg–1. We also made a detailed investigation of the p-TPPZ cathode's charge storage mechanism. This work will stimulate the further molecular design to develop organic batteries with both high energy and power density.

We studied the structure and transport properties of aromatic amine self-assembled monolayers (NH2-SAMs) on an Au surface. The oligophenylene and oligoacene amines with variable lengths can form a ...

A new charge transfer cocrystal of 1,2,4,5-tetracyanobenzene (TCNB)-phenazine (PTC) was prepared by solvent evaporation method. The donor and acceptor molecules of cocrystal are stacked face to face with a mixed-stacking, implying a strong charge transfer (CT) interactions in the cocrystal system. The spectroscopic studies, single-crystal X-ray diffraction structure, density functional theory (DFT) and Hirschfield surfaces calculations are carried out to explore the relationship between structure and properties of cocrystal system, which show that the intermolecular interactions in PTC are stronger than those of single components, leading to the stability and photophysical behaviors of cocrystal different from their constitute units. This study will be helpful for the design and preparation of multifunctional cocrystal materials.

Electrocatalytic CO2 reduction reaction (CO2RR) can store and transform the intermittent renewable energy in the form of chemical energy for industrial production of chemicals and fuels, which can dramatically reduce CO2 emission and contribute to carbon-neutral cycle. Efficient electrocatalytic reduction of chemically inert CO2 is challenging from thermodynamic and kinetic points of view. Therefore, low-cost, highly efficient, and readily available electrocatalysts have been the focus for promoting the conversion of CO2. Very recently, interface engineering has been considered as a highly effective strategy to modulate the electrocatalytic performance through electronic and/or structural modulation, regulations of electron/proton/mass/intermediates, and the control of local reactant concentration, thereby achieving desirable reaction pathway, inhibiting competing hydrogen generation, breaking binding-energy scaling relations of intermediates, and promoting CO2 mass transfer. In this review, we aim to provide a comprehensive overview of current developments in interface engineering for CO2RR from both a theoretical and experimental standpoint, involving interfaces between metal and metal, metal and metal oxide, metal and nonmetal, metal oxide and metal oxide, organic molecules and inorganic materials, electrode and electrolyte, molecular catalysts and electrode, etc. Finally, the opportunities and challenges of interface engineering for CO2RR are proposed.

Facile modulation of the rectification behavior of a molecular junction device was achieved by humidity and alkali metal ions using a series of carboxylic acid-terminated self-assembled monolayers ...

As simple and ubiquitous redox-active organic molecules, quinones participate in diverse electron transfer processes in chemistry and biological systems for energy transformation and signal transduction. We introduce here a practical exercise to study the redox potentials of benzoquinone and its two derivatives by combining the electrochemistry method with quantum chemistry computation. The practical reduction potentials of three quinones were measured by cyclic voltammetry experiment. Quantum chemistry computation, on the other hand, provided theoretical Gibbs free energy change and reduction potentials of the three quinones, which were found to be in line with the experimental results. Detailed thermodynamic energy analysis based on the computation results revealed that the reduction Gibbs free energy changes of the three quinones were mainly contributed from the electronic energies change of the molecules, while thermal energy and entropy played a relatively minor role. The energy levels of the lowest unoccupied molecular orbital (LUMO) of the three quinones, which were modulated by substituent groups and conjugation structures, were further identified as the main origin of the reduction potential. This experiment provides practical and theoretical training on the fundamental ideas involved in major courses like thermodynamics, quantum chemistry, electrochemistry, and organic chemistry, and promotes students to find the tie between macroscopic redox properties of chemicals and their microscopic molecular structures, a key topic in chemistry education.

In recent years, organic field-effect transistors (OFETs) have shown great potential for advanced protein biochips due to their inherent biocompatibility and high-throughput detectability. However, the development of OFET-based protein biochips is still at an early stage. On the one hand, single-biomarker determination is not sufficient for the diagnosis of cancer; thus, simultaneous monitoring of electrical signals toward multi-biomarkers is widely concerned and explored. On the other hand, an optimized functionalization strategy for efficient protein immobilization is another key to make OFET-based protein biochips accessible with improved detection performance. Herein, a facile functionalization strategy is developed for excellent charge-transport thin films by suppressing the gelation of diketopyrrolopyrrole (DPP)-based polymer semiconductors with the addition of the glutaraldehyde cross-linking agent. Besides, functional groups are introduced on the device surface for efficient attachment of antibodies as receptors via a condensation reaction, enabling simultaneous determination of α-fetoprotein biomarker and carcinoembryonic antigen biomarker with improved sensitivity and reliability. Therefore, the proposed high-throughput OFET-based protein biochip has the potential to be widely utilized in early liver cancer diagnosis.

The oxidation of π-d-conjugated coordination polymers (CCPs) accompanied with anion insertion has the merits of increasing the capacity and elevating the discharge voltages. However, previous reports on this mechanism either required more investigations or showed low capacity and poor cyclablity. Herein, triphenylene-catecholate-based two-dimensional CCPs are constructed by employing inactive transition-metal ions (Zn2+ ) as nodes, forming Zn-HHTP. Substantial characterizations and theoretical calculations indicate the successive storage of cations and anions by redox reactions of only ligands, leading to a high reversible capacity of ≈150 mAh g-1 at 100 mA g-1 and a remarkable capacity retention of 90 % after 1000 cycles. On the contrary, as a control experiment, the analogous CCPs (Cu-HHTP) with Cu2+ nodes, where both ligands and metal ions undergo redox reactions, accompanied by the storage of only Na+ cations, show a much poorer cyclability. These results highlight the importance of redox reactions of only ligands for long-term cycle life and the insight into the storage mechanisms deepens our understanding on CCPs for the further design of CCPs with high performance.

MicroRNA (miRNA) functions are tightly regulated by their sub-compartmental location in living cells, and the ability to imaging of mitochondrial miRNAs (mitomiRs) is essential for understanding of the related pathological processes. However, most existing DNA-based methods could not be used for this purpose. Here, we report the development of a DNA nanoreporter technology for imaging of mitomiRs in living cells through near-infrared (NIR) light-controlled DNA strand displacement reactions. The sensing function of the DNA nanoreporters are silent (OFF) during the delivery process, but can be photoactivated (ON) with NIR light after targeted mitochondrial localization, enabling spatially-restricted imaging of two types of cancer-related mitomiRs with improved detection accuracy. Furthermore, we demonstrate imaging of mitomiRs in vivo through spatiotemporally-controlled delivery and activation. Therefore, this study illustrates a simple methodology that may be broadly applicable for investigating the mitomiRs-associated physiological events.

Singlet diradicaloids hold great potential as semiconductors for organic field-effect transistors (OFETs). However, their relative low material and device stabilities impede the practical applications. Here, to achieve balanced stability and performance, two isomeric dibenzoheptazethrene derivatives with singlet diradical character were synthesized in a concise manner. Benefitting from the aromatic stabilization, both compounds display a small diradical character and large singlet-triplet gap, as corroborated by variable-temperature electron paramagnetic resonance spectra, single-crystal analysis, and theoretical calculations. OFET devices based on single crystals showed a high hole mobility of 0.15 cm2 V-1 s-1 , which is the highest for zethrene-based semiconductors. Both isomers exhibited remarkable material stability in air-saturated solutions as well as excellent bias-stress and storage stability in device under ambient air.

Conjugated polymers with well-balanced ambipolar charge transport is essential for organic circuits at low cost and large area with simplified fabrication techniques. Aiming at this point, herein, a novel asymmetric thiophene/pyridine-flanked diketopyrrolopyrrole-based copolymer (PPyTDPP–2FBT) is designed and synthesized. Due to the effect of incorporating F atoms on molecular energy alignment and conjugation conformation, the PPyTDPP–2FBT copolymer exhibits typical V-shaped ambipolar field-effect transfer characteristics with well-balanced hole and electron mobilities of 0.64 and 0.46 cm2 V−1 s−1, respectively. Furthermore, organic digital and analog circuits such as inverters and frequency doublers are successfully constructed based on solution-processed films of the PPyTDPP–2FBT copolymers which show a typical circuit operating mode with a high gain of 133 due to the well-balanced electrical properties. In addition, PPyTDPP–2FBT-based devices also demonstrate good stability and batch repeatability, suggesting their great potential applications in organic integrated electronic circuits.

Temperature-insensitive properties are attractive for most electronics, including polymeric semiconducting devices. Especially, polymeric field-effect transistors (FETs) with high mobility have been important research targets due to their broad applications. However, polymeric FETs with stable charge transport operating at extremely cold or hot zones are faced with enormous challenges. In this study, the polyacrylonitrile was found to significantly tune the sizes of pre-aggregates of polymers in solutions and the crystallinity of the polymeric films. The orientation of 5–25 μm linear grains in the films were prepared through the bar-coating process with polyacrylonitrile as an additive, which stabilized the electron mobility over a wide range of temperatures. The linear-grain morphology of the film contributed to reducing the holes and grain boundaries in the transport paths of carriers. Typically, the top-gate FETs based on P(NDI2OD-T2) displayed a stable electron transporting behavior from 200 to 460 K, with mobility greater than 3.5 cm2V−1s−1.

The performance of Li anodes is extremely affected by the solvation of Li ions, leading to preferential reduction of the solvation sheath and subsequent formation of fragile solid-electrolyte interphase (SEI), Li dendrites, and low coulombic efficiency (CE). Herein, we propose a novel strategy to regulate the solvation sheath, through the introduction of intermolecular hydrogen bonds with both the anions of Li salt and the solvent by small amount additives. The addition of such hydrogen bonds reduced the LUMO energy level of anions in electrolyte, promoted the formation of a robust SEI, reduced the amount of free solvent molecules, and enhanced stability of electrolytes. Based on this strategy, flat and dense lithium deposition was obtained. Even under lean electrolytes, at a current density of 1 mA cm-2 with a fixed capacity of 3 mAh cm-2 , the Li-Cu cells showed an impressive CE value of 99.2 %. The Li-LiFePO4 full cells showed long-term cycling stability for more than 1000 cycles at 1 C, with a total capacity loss of only 15 mAh g-1 .

Organic field-effect transistors (OFETs) are considered as one of the cost-effective biosensor devices with rapid detection capabilities and multiparameter responses. However, the functionalization processes on normal organic devices might impact the device performance for its further sensitive and reliable sensing applications. Herein, we develop a novel organic material, 2,6-bis(4-formylphenyl)anthracene (BFPA) for use as the protective and functional layer of OFET-based biosensors, enabling ultrasensitive determination of alpha-fetoprotein (AFP) with femtomolar accuracy in human serum. By monitoring changes of the source-drain current (Ids) and threshold voltage (Vth) electrical signals, the device exhibits improved reliability in detecting AFP biomarkers and is able to differentiate between liver cancer patients and healthy individuals. Featuring label-free determination, shorter analysis time, and lower sample volume, this ultrasensitive and reliable OFET-based biosensor displays numerous advantages over traditional strategies such as enzyme-linked immunosorbent assay and electrochemiluminescence immunoassay, demonstrating that the proposed OFET-based biosensors have broader analytical and clinical applications for early liver cancer diagnosis.

Two-dimensional (2D) organic semiconductor crystals (OSCs) are ideal platforms for investigating fundament materials as well as achieving high-performance organic field-effect transistors (OFETs). The surfactants played an important role in the 2DOSCs growth in previous studies. However, residual surfactants may cause performance degradation of devices. Herein, a simple and effective dual-function surfactant strategy is used to control the growth of large-area few-molecular-layer 2DOSCs The introduction of phosphatidylcholine decreases the interfacial tension and improves the crystal growth dynamics, resulting in high-quality and large-area few-molecular-layer 2,6-bis(4-hexylphenyl)anthracene (C6-DPA) 2DOSC. The additive also passivates charge traps, boosting the mobility of 2DOSC-based OFETs by almost threefold. This method is also suitable for the growth of various high-quality 2DOSCs, opening up a new avenue for high-quality 2DOSCs towards high-performance OFETs.

Single-atom catalysts (SACs) have obtained a great deal of attention in many catalytic fields due to the high atom utilization efficiency and high catalytic activity. Recently, great achievements on SACs have been made for thermocatalysis, electrocatalysis, and photocatalysis which play an important role in obtaining value-added products. However, it remains a great challenge to fabricate SACs with high metal loading and investigate their reaction mechanisms. Therefore, it is necessary to highlight the recent development of SACs in these fields to guide future research. In this review, we overviewed the thermocatalysis applications of SACs in CO oxidation, preferential oxidation of CO, water-gas shift reaction, methane conversion, methanol steam reforming, aqueous-phase reforming of methanol, hydrogenation of alkynes and dienes, hydrogenation of CO, and hydrogenation of substituted nitroarenes. Moreover, the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO2 reduction reaction (CO2RR), and N2 reduction reaction (N2RR) for photocatalytic and electrocatalytic fields were also overviewed. Lastly, the opportunities and challenges of SACs were pointed out.

The development of optical materials with room temperature phosphorescence (RTP) and white light emission (WLEDs) is highly desirable and remains a challenging task. Herein, a porous metal–organic framework PCN-921 with a high quantum yield (ΦF = 93.6%) was achieved. To make full use of the advantages of the high porosity of PCN-921, we hierarchically encapsulated different guest molecules coronene and rhodamine B (RhB) into the framework. Unsurprisingly, the hybrid material coronene@PCN-921 was obtained after in situ encapsulation of the guest coronene into the framework, and it exhibits obvious RTP behavior with a long phosphorescence lifetime of 62.5 ns. Subsequently, second guest RhB molecules were introduced after soaking in RhB solution and the material RhB@coronene@PCN-921 was achieved. Interestingly, it exhibits white light emission with the CIE coordinates of (0.29, 0.34), and can be used as a high performance WLED lamp. This is the first work on dual-functional hybrid dyes@MOFs with hierarchical guest encapsulation for RTP and white light emission, which suggests the potential applications of MOFs in multifunctional optical devices.

Stretchable electrodes are one of the essential building blocks for stretchable electronics. However, most of the reported stretchable electrodes show a considerable conductivity decrease under large stretchability. Until now, it has still been a big challenge to develop appropriate geometric structures to realize stretchable metal electrodes with a negligible conductivity change under large stretchability. Here, inspired by the armadillo, we develop a novel micro-foldable structure on polydimethylsiloxane (PDMS) using a suspended plasma etching method. This novel structure could endow the obtained stretchable electrodes with excellent properties including high metallic conductivity (>40 000 S cm−1) at released and stretched states, slight resistance change (13%) over a large tensile range (190%), a fully-covered conductive area, excellent cyclic operational stability (over 10 000 times), and a robust interface adhesion strength (>0.28 MPa). These figures of merit are very prominent compared to the reported stretchable gold electrodes, indicating the superiority of this novel micro-foldable structure. Furthermore, these stretchable electrodes show excellent performance in electromyography (EMG) signal detection, stretchable conducting wires and capacitive stretchable sensors. This work provides a novel and efficient avenue for the preparation of stretchable electronics.

Herein, we illustrate how the cooperation of intermolecular hydrogen bonds and conformation flexibility leads to the formation of diverse complex covalent nanostructures on the surface, while the relative abundance of the final products can be further tuned by adjusting the molar ratio and concentration of monomers.

The emerging π-d conjugated coordination polymers (CCPs) have attracted increasing attention in the past several years for various applications. However, to date, almost all the reported CCPs are based on a single type of chelating atom (e.g. N, S, O and Se) and only a few works have focused on the co-existence of heterochelating atoms in the ligands of CCPs. Herein, two Ni-based CCPs with N and S as co-chelating atoms were proposed for application in sodium-ion batteries (SIBs). The co-existence of N and S as chelating atoms resulted in high electrical conductivity and high stability, leading to a high capacity, excellent cyclability and high rate capability for the CCPs. Their electrochemical performances are superior to that of all the previously reported CCPs with only N or S as the chelating atom for SIBs. These results enrich the CCPs, deepen our understanding on the chemical states of CCPs and would stimulate further investigations of CCPs with heterochelating atoms for various applications.

Three anthracene derivatives, referred to as 2-phenyl anthracene (Ph-Ant), 2-thiazole anthracene (TZ-Ant), and 2-pentafluorophenyl anthracene (F5Ph-Ant), were designed and synthesized to reveal the effects of the electron-withdrawing substituents on the molecular packing structure and photoelectric properties of the anthracene core. As the electron-withdrawing abilities of the substituents increased, the molecular structures of the three semiconductors showed a progressive deterioration in intermolecular interactions and molecular accumulation, and the photoelectric properties became worse. Interestingly, the energy levels of the three semiconductors showed gradually decreasing changes with an enhancement of the electron-withdrawing abilities of the substituents, indicating a possible strategy for fabricating n-type anthracene derivative semiconductor materials.

Organic semiconductors with long-range exciton diffusion length are highly desirable for optoelectronics but currently remain rare. Here, the estimated diffusion length of singlet excitons (LD ) in 2,6-diphenyl anthracene (DPA) crystals grown by solvent evaporation was shown to be up to approximately 124 nm. These crystals showed a previously unseen parallelogram morphology with layer-by-layer edge-on molecular stacking, isotropic optical waveguiding, radiation rate and non-radiation rate constants of 0.15 and 0.26 ns-1 respectively, as well as good field-effect transistor hole mobility and theoretically computed strong electronic couplings as high as 109 meV. Photoresponse experiments revealed that the photoconductivity of DPA crystals is surprisingly not related to the radiative pathway but associated with rapid exciton diffusion to the crystal surface for charge separation and carrier bimolecular recombination. Taken together, DPA was shown to be a promising semiconducting material for a new organic optoelectronics paradigm.

In this article, an acid-responsive luminescent material, 1,4-di(quinoline-6-yl)buta-1,3-diyne (DQBD) is designed and synthesized. Upon different pH values, gradual changes of fluorescence colors for DQBD in both solution and solid phases are demonstrated due to the protonation effect. Moreover, such responsive characteristics can also be reversible, suggesting DQBD as a promising fluorescent material with great potential for reusable- and accurate-pH sensors in the future.

The tradeoff between sensitivity and detection range (maximum and minimum stretchability) is a key limitation in strain sensors; to resolve this, we develop an efficient and novel strategy herein to fabricate a highly sensitive and stretchable strain sensor inspired by the membrane–shell structure of poultry eggs. The developed sensor comprises a soft and stretchable surface-grafting polypyrrole (s-PPy) film (acting as the membrane) and a brittle Au film (acting as the shell), wherein both films complement each other at the electrical and mechanical levels. Au forms cracks under strain contributing to its high sensitivity and low detection limit, and s-PPy can bridge Au cracks and increase stretchability which has not been used in strain sensors before. The surface-grafting strategy not only enhances interface adhesion but also tunes the brittle property of native PPy to render it stretchable. Utilizing the synergetic effect of the membrane–shell complementary structure, the strain sensors achieve ultrahigh sensitivity (>107), large stretchability (100%), and an ultralow detection limit (0.1%), demonstrating significant progress in the field of strain sensors. The membrane–shell (Au/s-PPy)-structured strain sensor can successfully detect finger motion, wrist rotation, airflow fluctuation, and voice vibration; these movements produce strain in the range of subtle to marked deformations. Results evidence the ultrahigh performance and bright application prospects of the developed strain sensors.

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.

Aromatic diimides are one of the most important chromophores in the construction of n-type organic semiconductors, which lag far behind their p-type counterpart but are necessary for ambipolar transistors, p-n junctions and organic complementary circuits. Herein, we establish a facile one-pot domino synthetic protocol for aromatic diimides via palladium-catalyzed carbonylation of tetrabromo aromatic precursors. Taking tetrabromocorannulene (TBrCor) and tetrabromo-2,7-di-tert-butylpyrene (TBrPy) as the typical examples, we obtained diimide derivatives in yields of about 50 %, one order of magnitude higher than that of the traditional multi-step diimidization. As demonstrated in the case of corannulene diimide, the efficient diimidization not only allows the LUMO levels to be lowered significantly but also provides an ordered and closer packing structures, opening up possibilities to the development of n-type semiconducting materials based on a variety of aromatic systems.

Organic materials that show substantial reactivity under visible light have received considerable attention due to their wide applications in chemical and biological systems. Hemicyanine pigments possess a strong intramolecular donor-acceptor structure and thereby display intense absorption in the visible spectral region. However, most excitons are consumed via the twisted intramolecular charge-transfer (TICT) process, making hemicyanines generally inert to light. Herein, we describe the development of an amphiphilic hemicyanine dye whose aggregation could be easily regulated using salt or counterions. More importantly, its intrinsic photoreactivity was successfully induced by steric restriction and cofacial arrangement within the H-aggregate, thus creating an effective photobactericide. This strategy could be extended to the development of photocatalysts for photosynthesis and a photosensitizer for photodynamic therapy.

Two-dimensional (2D) nanorod meshes made of benzoperylene-1,3-dicyanotetrafluorobenzene (BP-1,3-DTFB) were formed via crystal transformation of the pre-existing BP microsheets. The transformation was driven by a cooperative effect of intermolecular charge-transfer and arene-perfluoroarene interactions. Epitaxial growth of cyan-emitting BP-1,3-DTFB nanorod meshes was directed by small lattice mismatch between BP and BP-1,3-DTFB, followed by the consumption of BP and the formation of BP-1,3-DTFB. Such a crystal transformation strategy can also be used to guide the formation of BP-1,4-dicyanotetrafluorobenzene (BP-1,4-DTFB) nanorod meshes. The present work reports a simple yet effective approach for the realization of aligned organic nanorod superstructures.

DFT study suggests that the C–H cleavage involved in the C(sp3)–H amination catalyzed by manganese perchlorophthalocyanine complex [MnIII(ClPc)]+ proceeds via hydride transfer (HYT), instead of hyd...

Copper/oxalic diamide-promoted dimerization of tetrachlorinated perylene bisimide to construct highly-fused diperylene bisimides through Ullmann coupling and zipper-mode double C-H activation has been developed in this study. This one-step reaction combining homocoupling with C-H activation proceeded smoothly under the action of inexpensive metal-ligand system. This protocol is expected to expand the available synthetic tools for condensed ring systems of perylene bisimide(PBIs).

Herein, two new poly(phenylene vinylene)-derivated semiconductors, poly(benzopyrrolone-p-phenylene-vinylene) (PBPPV) and poly(benzopyrrolone-di-p-phenylene-vinylene) (diPBPPV), are designed and synthesized with lactam groups as the electron-deficient and lateral extending units and phenylethylene as the emissive element for achieving integrated optoelectronic properties. Comprehensive characterization demonstrates that both PBPPV and diPBPPV are red-emissive materials with a photoluminescent quantum yield (PLQY) of up to 7% and exhibit well-balanced ambipolar transport properties with the electron and hole mobility approaching 4.5 × 10−4 cm2 V−1 s−1 and 3.0 × 10−4 cm2 V−1 s−1, respectively. This work provides valuable guidelines for further improvement of integrated optoelectronic conjugated polymers by rational molecular design.

By introducing the naphthyl group into the 2,6-positions of anthracene, two different anthracene derivatives, 2,6-di(2-naphthyl)anthracene (2,6-di(2-Na)Ant) and 2,6-di(1-naphthyl)anthracene (2,6-di(1-Na)Ant) were synthesized. The tiny change in the substitution site of the naphthyl group leads to a significant difference in the molecular packing and further exerts a great impact on their optoelectronic properties. Thin film field-effect transistors for 2,6-di(2-Na)Ant show charge transport mobility up to 2.1 cm2 V−1 s−1, while 2,6-di(1-Na)Ant demonstrates no mobility. Moreover, thin film phototransistors of 2,6-di(2-Na)Ant show a photoresponsivity of 6.9 × 103 A W−1, a high photosensitivity of 2.6 × 106 and an excellent detectivity of 3.4 × 1016 Jones, which is one of the highest performances of thin film organic phototransistors reported to date.

Herein, two kinds of vertical organic optoelectronic devices, vertical organic field-effect transistors (VOFETs) and light-emitting transistors (VOLETs), were constructed based on amorphous organic semiconductors of N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) as hole injecting and transport layers and tris(8-hydroxy-quinolinato) aluminum (Alq3) as the emitting layer. High device performances with a large on/off ratio of ∼6 × 103, current density of ∼40 mA cm-2, and fast response of ∼5 ms at a frequency of 20 Hz and a brightness of 126 cd m-2 were demonstrated for these two vertical devices with good device stability and repeatability. These results suggest the potential applications of amorphous organic semiconductors with good film-forming characteristics and easy device fabrication ability in vertical optoelectronic circuits.

In this work we present for the first time the nonvolatile resistive switching behavior of graphdiyne (GDY) film. We developed a simple approach to fabricate large-area homogeneous GDY films at an air/water interface, via catalytic homocoupling of hexaethynylbenzene at ambient temperature. The high uniformity, large size and low surface roughness of the as obtained GDY films to a large extent simplify the typical complex fabrication processes of carbon-based memristors. The rewritable memristors based on this ultrathin GDY film (about 7 nm) exhibit steady nonvolatile resistance switching behavior with excellent data retention capability (>103 s) and high on/off ratio (about 103). This is the first report on nonvolatile memristors based on pure continuous ultrathin GDY films which show clear write/erase switching properties. The electrical performances of the GDY memristors are significantly improved when Ag is used as a top electrode, which is likely due to the formation of Ag conductive filaments, as observed by HRTEM measurements. This study demonstrates that GDY films are promising candidates for carbon-based nonvolatile memristors.

A water-soluble macrocyclic host is reported, composed of alkoxyanthracene as the donor (D), and 4,4-bipyridinium as the acceptor (A). The intramolecular D-A structure renders the host highly photostable. However, the introduction of a strong electron-donating guest promotes the photodecomposition of alkoxyanthracene, yielding photolyzable host-guest complexes or aggregates.

Conjugated polymer (CP) films with high molecular order are attractive in polymeric optoelectronics, but challenging. Herein, we adopt a facile strategy including synergetic polymerization and self-assembly for crystalline CP films at a dynamic air/water interface. With poly(2,5-dihexyloxy-1,4-phenylenebutadiynylene) (poly-DHO-PBD) as one case shown from poly(butadiynylene) derivatives, large-area two-dimensional (2D) crystalline poly-DHO-PBD films with sizes of hundreds of micrometers and thicknesses down to tens of nanometers are successfully obtained from its 1,4-diethynyl-2,5-bis(hexyloxy)benzene (DEBHB) monomers by optimizing the interfacial Glaser-type reaction conditions, which can also be extended for the synthesis of four other poly(butadiynylene) derivatives. The high-quality crystalline CP films demonstrate efficient charge transport performance and excellent stability in electronic devices. This result opens a new avenue for preparing 2D crystalline CP films and would motivate increasing related lines of research on more complex functional CPs towards high performance polymeric optoelectronic devices and fundamental studies.

Surface-grafting polymers, also known as polymer brushes, have become an important tool for surface modification or functionalization. The strong covalent bond between the polymer brushes and the surface endow polymer brushes with several unique characteristics: precise control of surface property by the grafting process, better stability, easier patterning and so on. Thus, during the past few decades, surface-grafting polymers have gradually played an important role in the development of organic electronic devices, such as OFETs, OLEDs, OPVs, and so on. In this article, we will comprehensively review the recent progress in surface-grafting polymers, including their formation process and the utilization of surface-grafting polymers as functional materials of insulators, conductors and semiconductors in versatile organic electronic devices. Then, we will provide an outlook on the promising future of surface-grafting polymers in organic electronics.