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A quadrupolar compound Pyr-BA with two pyrrole-type nitrogen atoms doped externally was prepared in this work. In high contrast with other π ionic radicals, its cationic radical Pyr-BA⋅ + undergoes unusual symmetry-broken charge separation (SB-CS), generating the mixed valence complex of Pyr-BA +1-q ⋅⋅⋅Pyr-BA +1+q , where q is the degree of charge transfer. Variable-temperature (VT) single-crystal analysis, absorption and EPR experiments all confirmed that aggregation and lower temperature would help to facilitate this SB-CS process. Gibbs energy calculations and gauge-including magnetically induced current simulation both validate that, for Pyr-BA⋅ + , SB-CS behavior is more favorable than the conventional dimerization mode. To the best of our knowledge, this is the first study that shows solid single-crystal evidence for spontaneous SB-CS between identical ionic radicals. Such a unique phenomenon is of great significance both in terms of fundamental aspects and uncharted material science., (© 2023 Wiley-VCH GmbH.)

Enhancing the electrochemical stability and reversibility of redox-active organic molecules is crucial to improve the performance of non-aqueous redox flow batteries (RFBs). Compared with the widely adopted strategy of molecular engineering, we show in this study that tuning the intermolecular interaction between the active material with the supporting electrolyte is another feasible way to address the performance of non-aqueous organic RFBs. Combined with theoretical and experimental investigations, the influence of Lewis acidity of the supporting electrolyte cations and anions on the electrochemical stability and reversibility of bipyridine-based anode material is revealed. As a demonstration, a redox flow cell based on 4,4'-bipyridine anolyte and ferrocene catholyte shows greatly enhanced performance by using supporting electrolyte composed of soft Lewis acid and soft Lewis base. This study provides an alternative, yet highly effective way to addressing the cyclability of an organic compound for non-aqueous RFBs., (© 2022 Wiley-VCH GmbH.)

A B-N embedded nitrogen-annulated perylene has been successfully synthesized. The resultant molecule BN-NP is isoelectronic to coronene, but owns a five-membered pyrrole ring. Experiments and DFT calculations indicated that peripheral pyrrole and BN modifications endow BN-NP with various unique properties like bent structure, dual emission, efficient Lewis acidic response, peripheral aromaticity, narrowest energy band gap among all coronene isoelectronic structures and so on., (© 2022 Wiley-VCH GmbH.)

By virtue of strong molecular interactions, eutectic electrolytes provide highly concentrated redox-active materials without other auxiliary solvents, hence achieving high volumetric capacities and energy density for redox flow batteries (RFBs). However, it is critical to unveil the underlying mechanism in this system, which will be undoubtedly beneficial for their future research on high-energy storage systems. Herein, a general formation mechanism of organic eutectic electrolytes (OEEs) is developed, and it is found that molecules with specific functional groups such as carbonyl (CO), nitroxyl radical (NO•), and methoxy (OCH 3 ) groups can coordinate with alkali metal fluorinated sulfonylimide salts (especially for bis(trifluoromethanesulfonyl)imide, TFSI), thereby forming OEEs. Molecular designs further demonstrate that the redox-inactive methoxy group functionalized ferrocene derivative maintains the liquid OEE at both reduced and oxidized states. Over threefold increase in solubility is obtained (2.8 m for ferrocene derivative OEE) and high actual discharge energy density of 188 Wh L -1 (75% of the theoretical value) is achieved in the Li hybrid cell. The established mechanism presents new ways of designing desirable electrolytes through molecular interactions for the development of high-energy-density organic RFBs., (© 2021 Wiley-VCH GmbH.)

Organic compounds are promising candidates as battery materials because they can be sourced from sustainable resources, have tunable structures, and are cheap. However, the working voltage of battery cells containing organic compounds as positive electrodes is relatively lower than that of those containing an inorganic counterpart. In this work, a strategy was developed to increase the discharge voltage of battery cells by diluting the electron density of N-based redox centers in conjugated organic materials. In electron-rich heterocyclic compounds that utilize N as the redox center, pentatomic rings such as carbazole derivatives exhibited a higher atomic-dipole-moment-corrected Hirshfeld charge population compared with hexatomic rings, which led to a significant increase in the oxidation potential. As a result, polymeric indolocarbazole derivatives showed a high discharge voltage of 3.7-4.3 V vs. Li + /Li and good cycling performance. Such a strategy can be used to design high-voltage organic electrode materials containing other redox centers., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Symmetric batteries received an increasing research interest in the past few years because of their simplified fabrication process and reduced manufacturing cost. In this study, we propose the first dual-ion organic symmetric cell based on a molecular anion of 4,4'-(phenazine-5,10-diyl)dibenzoate. The alkali salt of 4,4'-(phenazine-5,10-diyl)dibenzoate allows a facile transport of cations and large anions, and remains stable in both oxidized and reduced states. The large potential difference between phenazine and benzoate results in a high cell voltage of 2.5 V and an energy density of 127 Wh kg -1 at a current rate of 1 C. The introduction of bipolar organic materials may further consolidate the development of symmetric batteries that are fabricated from abundant elements and environmentally friendly materials., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of symmetric squarylium dyes (SQDPA-X) with different halogen (X=F, Cl, Br, I) substituents have been developed. The photophysical properties could be facilely tuned by the halogen modulation effects. The strategy of incorporating different halogen substitutions into AIE active luminogens enables a facile approach for exploring new intriguing organic fluorescent dyes., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two novel 2D bisthienoacenes with annulated thiophene units at different positions were developed. Both 1,2- and 1,4-addition of the α,β-unsaturated ketone moieties lead to the major formation of four-fold alkylsilylethynyl substituted 2D heteroacenes (namely BTT-4TIPS and BTP-4TIPS). The photophysical, electrochemical properties, crystal packing structures, and charge carrier transport performances were investigated in detail., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Owing to the extraordinary properties, organic micro/nanocrystals are important building blocks for future low-cost and high-performance organic electronic devices. However, integrated device application of the organic micro/nanocrystals is hampered by the difficulty in high-throughput, high-precision patterning of the micro/nanocrystals. In this study, the authors demonstrate, for the first time, a facile capillary-assisted alternating-electric field method for the large-scale assembling and patterning of both 0D and 1D organic crystals. These crystals can be precisely patterned at the photolithography defined holes/channels at the substrate with the yield up to 95% in 1 mm 2 . The mechanism of assembly kinetics is systematically studied by the electric field distribution simulation and experimental investigations. By using the strategy, various organic micro/nanocrystal patterns are obtained by simply altering the geometries of the photoresist patterns on substrates. Moreover, ultraviolet photodetectors based on the patterned Alq3 micro/nanocrystals exhibit visible-blind photoresponse with high sensitivity as well as excellent stability and reproducibility. This work paves the way toward high-integration, high-performance organic electronic, and optoelectronic devices from the organic micro/nanocrystals., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Acene-based materials have promising applications for organic electronics but the major constrain comes from their poor stability. Herein a new strategy to stabilize reactive acenes, by fusion of an anti-aromatic pentalene unit onto the zigzag edges of two acene units to form a Z-shaped acene dimer, is introduced. The Z-shaped acene dimers are extremely stable and show a small energy gap resulting from intramolecular donor-acceptor interactions. X-ray crystallographic analysis revealed their unique geometry and one-dimensional slip-stack columnar structure. Besides optical and electrochemical characterizations, solution-processed field-effect transistors were also fabricated., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Three soluble and stable thienoacene-fused pentalene derivatives (1-3) with different π-conjugation lengths were synthesized. X-ray crystallographic analysis and density functional theory (DFT) calculations revealed their unique geometric and electronic structures due to the interaction between the aromatic thienoacene units and antiaromatic pentalene moiety. As a result, they all possess a small energy gap and show amphoteric redox behaviour. Time dependent (TD) DFT calculations were used to explain their unique electronic absorption spectra. These new compounds exhibited good thermal stability and ordered packing in solid state and thus their applications in organic field-effect transistors (OFETs) were also investigated. The highest field-effect hole mobility of 0.016, 0.036 and 0.001 cm(2)  V(-1)  s(-1) was achieved for solution-processed thin films of 1-3, respectively., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)