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We unravel the electronic structure of graphene nanoribbons in solution using two-dimensional electronic spectroscopy. We identify different excitons, their vibrational couplings and find that exciton diffusion or relaxation among the exiton sublevels takes place in ~300 fs.

Multi-component smart organic materials (MCSOMs) with stimuli-chromic behaviors have attracted significant attention due to their easily switchable photophysical properties and advanced applications. This review highlights the latest developments in multi-component stimuli-chromic organic materials activated by various stimuli, including light, heat, mechanical force, vapor, pH, and chemicals. Herein, we discuss the design strategies, stimuli-chromic mechanisms, and their potential applications in fields such as information encryption, sensors, biological imaging, and green printing. Also, the review provides a detailed classification and discussion of exciting stimuli-chromic properties of stimuli-chromic MCSOMs. Lastly, the current achievements, limitations, key challenges, and future prospects are summarized and discussed. This review may inspire further innovative research on multi-component stimuli-responsive smart organic materials, thus fostering further development of smart materials and devices. [ABSTRACT FROM AUTHOR]

Smart materials based on stimuli-fluorochromic π-conjugated solids (SFCSs) have aroused significant interest due to their versatile and exciting properties, leading to advanced applications. In this review, we highlight the recent developments in SFCS-based smart materials, expanding beyond organometallic compounds and light-responsive organic luminescent materials, with a discussion on the design strategies, exciting properties and stimuli-fluorochromic mechanisms along with their potential applications in the exciting fields of encryption, sensors, data storage, display, green printing, etc. The review comprehensively covers single-component and multi-component SFCSs as well as their stimuli-fluorochromic behaviors under external stimuli. We also provide insights into current achievements, limitations, and major challenges as well as future opportunities, aiming to inspire further investigation in this field in the near future. We expect this review to inspire more innovative research on SFCSs and their advanced applications so as to promote further development of smart materials and devices. [ABSTRACT FROM AUTHOR]

Achieving fast electrocatalytic nitrogen reduction reaction (NRR) at ambient conditions has an important implication to the low-cost synthesis of ammonia, a paramount raw material for agricultural and chemical industries. However, ambient NRR is severely challenged by the lack of active electrocatalysts and a serious competition between hydrogen evolution reaction (HER) and NRR. Herein, we report a low-cost, oxygen-deficient, and multivalent vanadium oxide (mVOx) nanosheets mixed with reduced graphene oxide (rGO) as an active electrocatalyst for NRR. The testing results show a high ammonia yield of 18.84 μg h−1 mgcat.−1 and a remarkable faradaic efficiency of 16.97% at −0.35 V versus reversible hydrogen electrode in a neutral 0.1 M Na2SO4 electrolyte. The outstanding performance is correlated by theoretical calculations to the hydrophilicity and high concentration of oxygen vacancies in mVOx, which promote nitrogen/water activation and lower the energy barrier for NRR. The presented insights of tailoring hydrophilicity via defect engineering are expected to significantly influence future designs of high-performance NRR electrocatalysts. [ABSTRACT FROM AUTHOR]

Organic cocrystals based on noncovalent intermolecular interactions (weak interactions) have aroused interest owing to their unpredicted and versatile chemicophysical properties and their applications. In this Minireview, we highlight recent research on organic cocrystals on reducing the aggregation‐caused quenching (ACQ) effect, tuning light emission, ferroelectricity and multiferroics, optical waveguides, and stimuli‐responsiveness. We also summarize the progress made in this field including revealing the structure–property relationships and developing unusual properties. Moreover, we provide a discussion on current achievements, limitations and perspectives as well as some directions and inspiration for further investigation on organic cocrystals. [ABSTRACT FROM AUTHOR]

Searching novel haloplumbate building units to construct three‐dimensional (3D) frameworks is very important and highly desirable because such materials would possess new physical properties and potential applications. Here, by employing tetrakis(N‐imidazolemethylene)methane(TIMM) as a structure‐directing agent, the first 3D haloplumbate framework constructed from unprecedented Lindqvist‐like highly coordinated [Pb6Br25]13− nanoclusters has been successfully prepared under hydrothermal condition, where all Pb2+ centres in [Pb6Br25]13− nanoclusters adopt seven‐/eight‐coordinated configurations. The as‐obtained material is a wide‐gap semiconductor (≈3.1 eV) and can be stable up to 320 °C. More importantly, this material has been demonstrated to show temperature‐dependent emission. Our results could provide a new strategy to explore novel metal–halide open‐framework materials. Mind the gap: The first 3D haloplumbate framework constructed from unprecedented Lindqvist‐like highly coordinated [Pb6Br25]13− nanoclusters was successfully obtained. The as‐prepared material is a wide‐gap semiconductor and shows an interesting temperature‐dependent photoluminescence. [ABSTRACT FROM AUTHOR]

Abstract: Structurally well‐defined graphene nanoribbons (GNRs) have attracted great interest because of their unique optical, electronic, and magnetic properties. However, strong π–π interactions within GNRs result in poor liquid‐phase dispersibility, which impedes further investigation of these materials in numerous research areas, including supramolecular self‐assembly. Structurally defined GNRs were synthesized by a bottom‐up strategy, involving grafting of hydrophilic poly(ethylene oxide) (PEO) chains of different lengths (GNR‐PEO). PEO grafting of 42–51 % percent produces GNR‐PEO materials with excellent dispersibility in water with high GNR concentrations of up to 0.5 mg mL−1. The “rod–coil” brush‐like architecture of GNR‐PEO resulted in 1D hierarchical self‐assembly behavior in the aqueous phase, leading to the formation of ultralong nanobelts, or spring‐like helices, with tunable mean diameters and pitches. In aqueous dispersions the superstructures absorbed in the near‐infrared range, which enabled highly efficient conversion of photon energy into thermal energy. [ABSTRACT FROM AUTHOR]

ABSTRACT Solution self-assembly of amphiphilic 'rod-coil' copolymers, especially linear block copolymers and graft copolymers (also referred to as polymer brushes), has attracted considerable interest, as replacing one of the blocks of a coil-coil copolymer with a rigid segment results in distinct self-assembly features compared with those of the coil-coil copolymer. The unique interplay between microphase separation of the rod and coil blocks with great geometric disparities can lead to the formation of unusual morphologies that are distinctly different from those known for coil-coil copolymers. This review presents the recent achievements in the controlled self-assembly of rod-coil linear block copolymers and graft copolymers in solution, focusing on copolymer systems containing conjugated polymers, liquid crystalline polymers, polypeptides, and polyisocyanates as the rod segments. The discussions concentrate on the principle of controlling over the morphology of rod-coil copolymer assemblies, as well as their distinctive optical and optoelectronic properties or biocompatibility and stimuli-responsiveness, which afford the assemblies great potential as functional materials particularly for optical, optoelectronic and biological applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1459-1477 [ABSTRACT FROM AUTHOR]

Förster resonance energy transfer (FRET) plays a critical role in organic optoelectronic materials. However, developing facile and effective strategies to achieve high‐efficiency energy harvesting of chromophores with aggregation‐caused quenching (ACQ) remains an appealing yet challenging task, that has not yet been explored. Herein, a subtly strategy, crystallization‐induced precise co‐assembly (CIPCA) involving a molecular “lightening agent,” to effectively improve FRET efficiency of ACQ chromophores is developed. Bis(phenylethynyl)anthracene (BPA) and bis(phenylethynyl)naphthacene (BPN) with significant ACQ effect are chosen as representative FRET donor and acceptor, respectively, and weakly‐fluorescent octafluoronaphthalene (OFN) acted as the “lightening agent.” Thanks to precise co‐assembly with OFN, the PLQY of solid BPA is enhanced by 107%, and the BPN powder can be unprecedentedly lighted. More importantly, through such powerful CIPCA, the monotonous and weak emission for BPA@BPN can be remarkably regulated to colorful and much brighter ones with FRET efficiency improvement of as high as 180–270%. An in‐depth understanding of FRET regulation is elucidated through a precise correlation of the supramolecular structures and properties. Such achievements allow to successfully fabricate distinct multi‐stimuli‐responsive fluorescent patterns and highly‐emissive colorful flowers with high flexibility. This research provides an efficient strategy to improve the FRET efficiency of ACQ pairs. [ABSTRACT FROM AUTHOR]

Molecular doping is an effective method to enhance the charge carrier density for reducing the contact resistance and improving the charge mobility in organic field‐effect transistors (OFETs). Previous reports mainly focus on the strong dopants with the EAdopant > IEOSC (p‐type) or IEdopant < EAOSC (n‐type) to enable the efficient charge transfer (EA: electron affinity; IE: ionization energy; OSC: organic semiconductor). However, the effects of weak dopants on the OFET performance of OSC are rarely investigated. Thus, in this study, it is demonstrated that two new fluorinated compounds (Tetrafluorophthalonitrile (TFP) and Octafluoronaphthalene (OFN)) can act as weak dopants in thin film of TIPS‐Pentacene (TIPS). Although they exhibit unmatched EAs (3.45 eV for TFP and 3.44 eV for OFN) compared to the IE (5.17 eV) of the host TIPS, they still can fulfill the p‐type doping with the OSC matrix. Systematic structural and electrical characterization reveals the important role of the formed charge‐transfer interaction and the improved crystallinity in enhancing the carrier mobility. The doped poly(3‐hexylthiophene) is also investigated to confirm the universality of the weak dopants. The study should provide a new thought for the exploitation of novel planar soluble weak dopants in OFETs. An effective p‐doping process can be fulfilled with weak dopants although they exhibit unmatched energy levels with the host matrix. After doping, the performance of solution‐processed OFETs is improved significantly, which can attribute to the increased charge concentration, decreased trap density, reduced contact resistance, and enhanced molecular packing order in film. [ABSTRACT FROM AUTHOR]