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It remains challenging to comprehensively understand the packing models of conjugated polymers, in which side chains play extremely critical roles. The side chains are typically flexible and non‐conductive and are widely used to improve the polymer solubility in organic solutions. Herein, a buffer chain model is proposed to describe link between conjugated backbone and side chains for understanding the relationship of crystallization competition of conductive conjugated backbones and non‐conductive side chains. A longer buffer chain is beneficial for alleviating such crystallization competition and further promoting the spontaneous packing of conjugated backbones, resulting in enhanced charge transport properties. Our results provide a novel concept for designing conjugated polymers towards ordered organization and enhanced electronic properties and highlight the importance of balancing the competitive interactions between different parts of conjugated polymers. [ABSTRACT FROM AUTHOR]

Incorporating heteroatoms can effectively modulate the molecular optoelectronic properties. However, the fundamental understanding of BN doping effects in BN‐embedded polycyclic aromatic hydrocarbons (PAHs) is underexplored, lacking rational guidelines to modulate the electronic structures through BN units for advanced materials. Herein, a concise synthesis of novel B2N2‐perylenes with BN doped at the bay area is achieved to systematically explore the doping effect of BN position on the photophysical properties of PAHs. The shift of BN position in B2N2‐perylenes alters the π electron conjugation, aromaticity and molecular rigidness significantly, achieving substantially higher electron transition abilities than those with BN doped in the nodal plane. It is further clarified that BN position dominates the photophysical properties over BN orientation. The revealed guideline here may apply generally to novel BN‐PAHs, and aid the advancement of BN‐PAHs with highly‐emissive performance. [ABSTRACT FROM AUTHOR]

The article focuses on the genome sequencing of Dendrobium thyrsiflorum, emphasizing its implications for understanding the genetic basis of important horticultural traits such as flower color, shape, and environmental adaptability. It explores genomic insights into the terpenoid biosynthetic pathway and the evolution of specific genes linked to flower development and pigmentation.

Conjugated polymers that can efficiently transport both ionic and electronic charges have broad applications in next‐generation optoelectronic, bioelectronic, and energy storage devices. To date, almost all the conjugated polymers have hydrophobic backbones, which impedes efficient ion diffusion/transport in aqueous media. Here, we design and synthesize a novel hydrophilic polymer building block, 4a‐azonia‐naphthalene (AN), drawing inspiration from biological systems. Because of the strong electron‐withdrawing ability of AN, the AN‐based polymers show typical n‐type charge transport behaviors. We find that cationic aromatics exhibit strong cation‐π interactions, leading to smaller π–π stacking distance, interesting ion diffusion behavior, and good morphology stability. Additionally, AN enhances the hydrophilicity and ionic‐electronic coupling of the polymer, which can help to improve ion diffusion/injection speed, and operational stability of organic electrochemical transistors (OECTs). The integration of cationic building blocks will undoubtedly enrich the material library for high‐performance n‐type conjugated polymers. [ABSTRACT FROM AUTHOR]

The backbone conformation plays a vital role in the solution aggregation behavior and photophysical and electrical properties of conjugated polymers. Previous studies indicated that the backbone conformation modification mainly relied on introducing various functional groups. However, regulating the molecular conformation through non‐covalent interactions is highly susceptible to external factors such as solvents and temperature. Herein, four isoindigo‐based polymers, IIDDP, IIDDP‐C0, IIDDP‐C1, and IIDDP‐C2, are developed with distinct chain conformation. Covalent bonds are employed to fix the dihedral angle of the donor fragment and then control the main‐chain conformation. Due to conformation‐locking, it was observed that the planarization of the main chain from the solution to the thin film could not be achieved in the desired polymers with twisted backbones. Further investigations revealed that the relationship between the backbone conformation and the solution‐state supramolecular structures play a critical role in controlling solid‐state microstructures and optoelectronic performance of conjugated polymers. [ABSTRACT FROM AUTHOR]

SUMMARY: Saururus chinensis, an herbaceous magnoliid without perianth, represents a clade of early‐diverging angiosperms that have gone through woodiness–herbaceousness transition and pollination obstacles: the characteristic white leaves underneath inflorescence during flowering time are considered a substitute for perianth to attract insect pollinators. Here, using the newly sequenced S. chinensis genome, we revisited the phylogenetic position of magnoliids within mesangiosperms, and recovered a sister relationship for magnoliids and Chloranthales. By considering differentially expressed genes, we identified candidate genes that are involved in the morphogenesis of the white leaves in S. chinensis. Among those genes, we verified – in a transgenic experiment with Arabidopsis – that increasing the expression of the "pseudo‐etiolation in light" gene (ScPEL) can inhibit the biosynthesis of chlorophyll. ScPEL is thus likely responsible for the switches between green and white leaves, suggesting that changes in gene expression may underlie the evolution of pollination strategies. Despite being an herbaceous plant, S. chinensis still has vascular cambium and maintains the potential for secondary growth as a woody plant, because the necessary machinery, i.e., the entire gene set involved in lignin biosynthesis, is well preserved. However, similar expression levels of two key genes (CCR and CAD) between the stem and other tissues in the lignin biosynthesis pathway are possibly associated with the herbaceous nature of S. chinensis. In conclusion, the S. chinensis genome provides valuable insights into the adaptive evolution of pollination in Saururaceae and reveals a possible mechanism for the evolution of herbaceousness in magnoliids. Significance Statement: The Saururus chinensis genome provides an important new resource for the understanding of the "rapid radiation" of early angiosperms, coined by Darwin as an "abominable mystery," and recovered a sister relationship for magnoliids and Chloranthales. Experiments and bioinformatics analyses reveal the molecular mechanism for the pollination‐related organ morphogenesis (white leaves during flowering time) in S. chinensis and an adaptive evolution of pollination strategy in Saururaceae, and provide valuable insights into the woodiness–herbaceousness transition in magnoliids. [ABSTRACT FROM AUTHOR]

Molecular ordering of conjugated polymers both in solution‐state aggregates and in solid‐state microstructures is a determining factor of the charge transport properties in optoelectronic devices. However, the effect of backbone conformation in conjugated polymers on assembly structures is still unclear. Herein, to understand such backbone conformation effect, three novel chlorinated benzodifurandionge‐based oligo(p‐phenylene vinylene) (BDOPV) polymers are systematically developed. These BDOPV‐based polymers exhibit significantly twisted backbone conformation (near 90° interunit torsion angle) between conjugated units, which can prevent polymer chains from forming ordered assembly structures by increasing conformational energy penalty in closely packed chains. A higher rotational barrier of the torsion angle would further prevent polymer chains from assembling, finally resulting in nonaggregated chains in solution and highly disordered solid‐state packing structures. This work will deepen the understanding of the relationship between polymer backbone conformation and assembly structures, contributing to the exploration of the structure–property relationship of polymers. [ABSTRACT FROM AUTHOR]

Despite the remarkable synthetic accomplishments in creating diverse polycyclic aromatic hydrocarbons with B−N bonds (BN‐PAHs), their optoelectronic applications have been less exploited. Herein, we report the achievement of high‐mobility organic semiconductors based on existing BN‐PAHs through a "periphery engineering" strategy. Tetraphenyl‐ and diphenyl‐substituted BN‐anthracenes (TPBNA and DPBNA, respectively) are designed and synthesized. DPBNA exhibits the highest hole mobility of 1.3 cm2 V−1 s−1 in organic field‐effect transistors, significantly outperforming TPBNA and all the reported BN‐PAHs. Remarkably, this is the first BN‐PAH with mobility over 1 cm2 V−1 s−1, which is a benchmark value for practical applications as compared with amorphous silicon. Furthermore, high‐performance phototransistors based on DPBNA are also demonstrated, implying the high potential of BN‐PAHs for optoelectronic applications when the "periphery engineering" strategy is implemented. [ABSTRACT FROM AUTHOR]

Strong interchain interactions of conjugated polymers usually result in poor miscibility with molecular dopants, limiting the doping efficiency because of uncontrolled phase separation. We have developed a strategy to achieve efficient charge‐transport and high doping miscibility in n‐doped conjugated polymers. We solve the miscibility issue through disorder side‐chains containing dopants better. Systemic structural characterization reveals a farther side‐chain branching point will lead to higher disorders, which provides appropriate sites to accommodate extrinsic molecular dopants without harming original chain packings and charge‐transport channels. Therefore, better sustainability of solid‐state microstructure is obtained, yielding a stable conductivity even when overloading massive dopants. This work highlights the importance of realizing high host‐dopant miscibility in molecular doping of conjugated polymers. [ABSTRACT FROM AUTHOR]

Introducing BN units into polycyclic aromatic hydrocarbons expands the chemical space of conjugated materials with novel properties. However, it is challenging to achieve accurate synthesis of BN‐PAHs with specific BN positions and orientations. Here, three new parent B2N2‐perylenes with different BN orientations are synthesized with BN‐naphthalene as the building block, providing systematic insight into the effects of BN incorporation with different orientations on the structure, (anti)aromaticity, crystal packing and photophysical properties. The intermolecular dipole–dipole interaction shortens the π–π stacking distance. The crystal structure, (anti)aromaticity, and photophysical properties vary with the change of BN orientation. The revealed BN doping effects may provide a guideline for the synthesis of BN‐PAHs with specific stacking structures, and the synthetic strategy employed here can be extended toward the synthesis of larger BN‐embedded PAHs with adjustable BN patterns. [ABSTRACT FROM AUTHOR]

The role of solution aggregates on the charge transport process of conjugated polymers in electronic devices has gained increasing attention; however, the correlation of the charge carrier mobilities between the solution aggregates and the solid‐state films remains elusive. Herein, three polymers, FBDOPV‐2T, FBDOPV‐2F2T, and FBDOPV‐4F2T, are designed and synthesized with distinct aggregation behavior in solution. By combining contact‐free ultrafast terahertz (THz) spectroscopy and field‐effect transistor measurements, we track the charge carrier mobility of the aggregates of these polymers from the solution to the thin‐film state. Remarkably, the mobility of these three polymers is found to follow nearly the same trend (FBDOPV‐2T>FBDOPV‐2F2T≫FBDOPV‐4F2T) in both solutions and thin‐film states. The quantitative mobility correlation indicates that the charge transport properties of solution aggregates play a critical role in determining the thin‐film charge transport properties and final device performance. Our results highlight the importance of investigating and controlling solution aggregation structures towards efficient organic electronic devices. [ABSTRACT FROM AUTHOR]

Crystal structure of conjugated molecules and polymers is fundamentally critical to understand their multilevel microstructures, carrier transport, and diverse functions. However, to determine the crystal structure of conjugated polymers is a significant challenge, mainly due to the poor crystallinity, weak diffraction, and instability under high‐energy radiation. Here, we build the possible crystal structures of eight typical conjugated polymers, covering several widely used molecular segments in organic optoelectronics. We model the packing structures of these seed polymers based on synchrotron X‐ray diffractions and molecular simulations. These crystal structures provide a new platform to predict the packing structures of more related polymer systems, extending the molecular scope. Based on this polymer crystal structure database, the multiscale microstructures and charge transport properties of conjugated polymers can be predicted before experiments. This study sets up a polymer crystal structure database to eliminate the current trial‐and‐error approaches and accelerating the design of high‐performance conjugated polymers. [ABSTRACT FROM AUTHOR]

Doping of polymeric semiconductors limits the miscibility between polymers and dopants. Although significant efforts have been devoted to enhancing miscibility through chemical modification, the electrical conductivities of n‐doped polymeric semiconductors are usually below 10 S cm−1. We report a different approach to overcome the miscibility issue by modulating the solution‐state aggregates of conjugated polymers. We found that the solution‐state aggregates of conjugated polymers not only changed with solvent and temperature but also changed with solution aging time. Modulating the solution‐state polymer aggregates can directly influence their solid‐state microstructures and miscibility with dopants. As a result, both high doping efficiency and high charge‐carrier mobility were simultaneously obtained. The n‐doped electrical conductivity of P(PzDPP‐CT2) can be tuned up to 32.1 S cm−1. This method can also be used to improve the doping efficiency of other polymer systems (e.g. N2200) with different aggregation tendencies and behaviors. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: By combination of two special structural units, a boron‐nitrogen‐fused polycyclic aromatic hydrocarbon and azulene with strong intramolecular dipoles, a novel BN aromatics, BN‐Az, has been designed and synthesized with unique characteristics. The structure, optical and electrochemical properties, as well as charge transport property of BN‐Az have been investigated. Notably, BN‐Az selectively responds to fluoride ions and protons with a significant color change, which could also be monitored by NMR spectra and single‐crystal X‐ray analysis, indicating its potential as an effective ion sensing material in stimuli‐responsive electronic devices. [ABSTRACT FROM AUTHOR]

Molecular doping plays an important role in the modification of carrier density of organic semiconductors thus enhancing their optoelectronic performance. However, efficient n‐doping remains challenging, especially owing to the lack of strongly reducing and air‐stable n‐dopants. Herein, an N‐heterocyclic carbene (NHC) precursor, DMImC, is developed as a thermally activated n‐dopant with the excellent stability in air. Its thermolysis in situ regenerates free NHC and subsequently dopes typical organic semiconductors. In sequentially doped FBDPPV films, DMImC does not disturb the π–π packing of the polymer and achieves good miscibility with the polymer. As a result, a high electrical conductivity of up to 8.4 S cm−1 is obtained. Additionally, the thermally activated doping and the excellent air stability permit DMImC to be noninteractively co‐processed with polymers in air. Our results reveal that DMImC can be served as an efficient n‐dopant suitable for various organic semiconductors. [ABSTRACT FROM AUTHOR]

High‐spin conjugated radicals have great potential in magnetic materials and organic spintronics. However, to obtain high‐spin conjugated radicals is still quite challenging due to their poor stability. We report the successful synthesis and isolation of a stable triplet conjugated diradical, 10,12‐diaryldiindeno[1,2‐b:2′,1′‐e]pyrazine (m‐DIP). With the m‐xylylene analogue skeleton containing electron‐deficient sp2‐nitrogen atoms, m‐DIP displays significant aromatic character within its pyrazine ring and its spin density mainly delocalizes on the meta‐pyrazine unit, making it a triplet ground state conjugated diradical. Our work provides an effective "spin density tuning" strategy for stable high‐spin conjugated radicals. [ABSTRACT FROM AUTHOR]

In the past few decades, conjugated polymers have aroused extensive interest in organic electronic applications. The electrical performance of conjugated polymers has a close relationship with their backbone conformation. The conformation of the polymer backbone strongly affects the πelectron delocalization along polymer chains, the energy band gap, interchain interactions, and further affects charge transport properties. To realize a rigid coplanar backbone that usually possesses efficient intrachain charge transport properties and enhanced π–π stackings, such conformation control becomes a useful strategy to achieve high‐performance (semi)conducting polymers. This minireview summarizes the most important polymer structures through conformation control at the molecular level, and then divides these rigid coplanar conjugated polymers into three categories: 1) noncovalent interactions locked conjugated polymers; 2) double‐bond linked conjugated polymers; 3) ladder conjugated polymers. The effect of the conformation control on physical nature, optoelectronic properties, and their device performance is also discussed, as well as the challenges of chemical synthesis and structural characterization. [ABSTRACT FROM AUTHOR]

Controlling the solution‐state aggregation of conjugated polymers for producing specific microstructures remains challenging. Herein, a practical approach is developed to finely tune the solid‐state microstructures through temperature‐controlled solution‐state aggregation and polymer crystallization. High temperature generates significant conformation fluctuation of conjugated backbones in solution, which facilitates the polymer crystallization from solvated aggregates to orderly packed structures. The polymer films deposited at high temperatures exhibit less structural disorders and higher electron mobilities (up to two orders of magnitude) in field‐effect transistors, compared to those deposited at low temperatures. This work provides an effective strategy to tune the solution‐state aggregation to reveal the relationship between solution‐state aggregation and solid‐state microstructures of conjugated polymers. [ABSTRACT FROM AUTHOR]

Realizing high polymer chain orientation and ordered thin‐film microstructures is beneficial for efficient charge transport of conjugated polymers. However, achieving a high alignment degree remains a challenge due to the sensitive nature of polymers to the processing conditions. By simply varying concentrations during a dip‐coating method, the component of polymer aggregates that adopt the planar backbones is enlarged and the ensuing assembly process is promoted. Herein, highly oriented polymer thin films of an isoindigo‐based conjugated polymer (PII‐2T) are prepared to enhance polymer orientation resulting in a drastic booming in carrier mobilities of organic field‐effect‐transistors (OFETs). The maximum mobility from aligned polymer films increases by up to 8.3 cm2 V−1 s−1, which is tenfold beyond the value evaluated from the unaligned direction or traditional spin‐coated samples. The enhanced orientation can also reduce the adverse effects of the contact resistance and facilitate charge transport in transistors. This work demonstrates that the highly aligned conjugated polymer films can be approached by the dip‐coating method while offers a latent cornerstone toward understanding the critical role of processing‐related parameters in determining morphology of solution‐coated thin films. [ABSTRACT FROM AUTHOR]

Aim: To investigate the clinicopathologic characteristic and fertility results of patients with mucinous borderline ovarian tumors (MBOTs), and the effects of intraepithelial carcinoma (IECA) on them. Methods: Fifty‐two patients treated for MBOTs with or without IECA were retrospectively analyzed. Results: Patients with IECA were more frequently observed at stage Ic (3/12 vs 1/40, P = 0.034) and accompanied by microinvasive carcinoma (3/12 vs 1/40, P = 0.034). The detected rate of IECA by intraoperative frozen section (5/12, 41.7%) was much lower than that of MBOTs (82.5%, P = 0.010). About 61.5% patients in our study underwent fertility‐sparing surgery. Follow‐up information was retained completely in 41 patients. And all four tumor recurrences were observed (9.8%) in conservative surgery group in 66 months, though there was no statistical association (P = 0.280). There were three patients who recurred more than once, even one occurred tumor‐related death. Only one recurrent patient was in IECA group (P > 0.05). However, patients with IECA were more likely to receive adjuvant chemotherapy (3 of 12 vs 0 of 40, P = 0.010) and surgical staging (75% vs 52.5%, P = 0.200). As for fertility results, nine patients wished to be pregnant and seven of them (77.8%) were successful. Conclusion: For young patients with MBOTs, fertility results are satisfactory after conservative surgery. But patients should be fully informed about the relative high recurrent rate. And IECA has no statistical negative effects on MBOTs till now, but a long‐term follow‐up is required. [ABSTRACT FROM AUTHOR]

Low n‐doping efficiency and inferior stability restrict the thermoelectric performance of n‐type conjugated polymers, making their performance lag far behind of their p‐type counterparts. Reported here are two rigid coplanar poly(p‐phenylene vinylene) (PPV) derivatives, LPPV‐1 and LPPV‐2, which show nearly torsion‐free backbones. The fused electron‐deficient rigid structures endow the derivatives with less conformational disorder and low‐lying lowest unoccupied molecular orbital (LUMO) levels, down to −4.49 eV. After doping, two polymers exhibited high n‐doping efficiency and significantly improved air stability. LPPV‐1 exhibited a high conductivity of up to 1.1 S cm−1 and a power factor as high as 1.96 μW m−1 K−2. Importantly, the power factor of the doped LPPV‐1 thick film degraded only 2 % after 7 day exposure to air. This work demonstrates a new strategy for designing conjugated polymers, with planar backbones and low LUMO levels, towards high‐performance and potentially air‐stable n‐type polymer thermoelectrics. [ABSTRACT FROM AUTHOR]

Considerable efforts have been devoted to achieving stable acene derivatives for electronic applications; however, the instability is still a major issue for such derivatives. To achieve higher stability with minimum structural change, CC units in the acenes were replaced with isoelectronic BN units to produce a novel BN‐embedded tetrabenzopentacene (BNTBP). BNTBP, with a planar structure, is highly stable to air, moisture, light, and heat. Compared with its carbon analogue tetrabenzopentacene (TBP), BN embedment lowered the highest occupied molecular orbital (HOMO) energy level of BNTBP, changed the orbital distribution, and decreased the HOMO orbital coefficients at the central carbon atoms, which stabilize BNTBP molecules upon exposure to oxygen and sunlight. The single‐crystal microribbons of BNTBP exhibited good performance in field‐effect transistors (FETs). The high stability and good mobility of BNTBP indicates that BN incorporation is an effective approach to afford stable large‐sized acenes with desired properties. [ABSTRACT FROM AUTHOR]

The joint of the donor and acceptor moieties allows a facile and effective strategy to develop novel organic conjugated materials. However, few pieces of work report the understanding of the donor–acceptor interactions at the molecular level. Herein, we developed three small molecules containing one acceptor motif with different amounts of the donor unit. By combining theoretical calculations and energy level characterization, the lowest unoccupied molecular orbital (LUMO) levels of the three molecules were proven to be almost identical. The molecular packing modes were evaluated from crystal structure prediction. Owing to the donor–acceptor interactions, the packing mode can be tuned from a 1D slipped stacking to a 2D brick layer. The 2D molecular packing and charge transport channel endowed the materials a higher electron mobility of 3.29 cm2 V−1 s−1 in the single‐crystal field‐effect transistors after such modulation. [ABSTRACT FROM AUTHOR]

p- or n-Dopants have played significant roles in the improvement of organic electronic devices through the controllable doping of organic semiconductors. However, there has been little study of air-stable n-dopants under ambient conditions with strong doping capability due to the low electron affinities of organic semiconductors. Herein, a 1,4-dihydropyridine-based derivative is designed and facilely synthesized as an efficient n-dopant. The doping process is systematically investigated by UV-vis-NIR spectroscopy in solution and ultraviolet photoelectron spectroscopy in the solid state. Excellent conductivities are obtained for a variety of doped n-type semiconductors via a simple solution process without further treatment, suggesting a broad class of 1,4-dihydropyridine derivatives could be used as n-dopants in future organic electronic devices. [ABSTRACT FROM AUTHOR]

A new electron-deficient unit with a fused 5-membered heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with a cyclohepta-4,6-diene-1,3-diimde unit. The imide bridge endows dithienylbenzenebisimide (BBI) with a fixed planar configuration and low energy levels for both the highest occupied molecular orbital (HOMO; −6.24 eV) and the lowest unoccupied molecular orbit (LUMO; −2.57 eV). Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm2 V−1 s−1, which indicates that the BBI is a promising n-type building block for optoelectronics. [ABSTRACT FROM AUTHOR]

Organic electron-acceptor materials play an important role in organic electronics, especially in organic bulk heterojunction (BHJ) solar cells. Recently, many non-fullerene small molecular acceptors have been developed, in which aromatic fused-imides were proven to be a promising family of excellent electron acceptors. We developed a series of acenaphtho[1,2- k]fluoranthene-fused diimides, AFIs ( AFI1, AFI2 and AFI3), employing the Diels-Alder reaction as the crucial synthetic step. With electron-withdrawing diimide groups in their large conjugated backbone, AFIs display a LUMO level around −3.50 eV. These AFI compounds were used as the electron acceptors to fabricate organic photovoltaic devices. The power conversion efficiency (PCE) of up to 2.37 % was achieved with a high open-circuit voltage ( Voc) up to 0.96 V. [ABSTRACT FROM AUTHOR]

Organic field-effect transistors (OFETs) have attracted much attention for the next-generation electronics. Despite of the rapid developments of OFETs, operational stability is a big challenge for their commercial applications. Moreover, the actual mechanism behind the degradation of electron transport is still poorly understood. Here, the electrical characteristics of poly{[ N, N-9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)} (P(NDI2OD-T2)) thin-film transistors (TFTs) as a function of semiconductor/dielectric interfacial property and environment are systematically investigated, in particular, how the copresence of water, oxygen, and active hydrogen on the surface of dielectric leads to a sharp drop-off in threshold voltage. Evidence is found that an acid-base neutralization reaction occurring at the interface, as a combined effect of the chemical instability of dielectrics and the electrochemical instability of organic semiconductors, contributes to the significant electron trapping on the interface of P(NDI2OD-T2) TFTs. Two strategies, increasing the intrinsic electrochemical stability of semiconductor and decreasing the chemical reactivity of gate dielectric, are demonstrated to effectively suppress the reaction and thus improve the operational stability of n-type OFETs. The results provide an alternative degradation pathway to better understand the charge transport instability in n-type OFETs, which is advantageous to construct high-performance OFETs with long-term stability. [ABSTRACT FROM AUTHOR]

A novel electron-deficient building block, 5,5′-diazaisoindigo ( 5DNIID), was synthesized through a facile method in good yield. As a derivative of isoindigo, 5DNIID shows an ultra-low LUMO level of −3.92 eV after incorporation of two electron-deficient nitrogen atoms into the para-position of the amine groups in the isoindigo π skeleton. Modified polymerization conditions were applied to efficiently afford the donor-acceptor (D-A) conjugated polymer 5DNIID-2T, which exhibited a p-type charge transport property. [ABSTRACT FROM AUTHOR]

A series of tetrafluorine-substituted small molecules with a D1-A-D2-A-D1 linear framework based on indacenodithiophene and difluorobenzothiadiazole is designed and synthesized for application as donor materials in solution-processed small-molecule organic solar cells. The impacts of thiophene π-bridge and multiple fluorinated modules on the photophysical properties, the energy levels of the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO), charge carrier mobility, the morphologies of blend films, and their photovoltaic properties as electron donor material in the photoactive layer are investigated. By incorporating multiple fluorine substituents of benzothiadiazole and inserting two thiophene spacers, the fill factor ( FF), open-circuit voltage, and short-circuit current density are dramatically improved in comparison with fluorinated-free materials. With the solvent vapor annealing treatment, further enhancement in charge carrier mobility and power conversion efficiency (PCE) are achieved. Finally, a high PCE of 8.1% with very-high FF of 0.76 for BIT-4F- T/PC71BM is achieved without additional additive, which is among one of the highest reported for small-molecules-based solar cells with PCE over 8%. The results reported here clearly indicate that high PCE in solar cells based small molecules can be significantly increased through careful engineering of the molecular structure and optimization on the morphology of blend films by solvent vapor annealing. [ABSTRACT FROM AUTHOR]

New BN-embedded, thiophene-fused, polycyclic aromatic compounds with planar geometry were designed and synthesized. The molecules showed excellent stability and chemical robustness. Postfunctionalization on this skeleton was demonstrated with a series of electrophilic bromination, palladium-catalyzed cross-coupling, and Knoevenagel condensation reactions. The π skeleton remained intact during these late-stage transformations. The optical and electronic properties have been well tuned through incorporation of electron-rich and -deficient groups on the backbone. This work shows the great advantage of the postfunctionalization strategy on BN-containing polycyclic aromatic compounds for fast diversification and materials screening. [ABSTRACT FROM AUTHOR]

Replacement of CC unit with its isoelectronic BN unit in aromatics provides a new class of molecules with appealing properties, which have attracted great attention recently. In this Concept, we focus on BN-substituted polycyclic aromatics with fused structures, and review their synthesis, photophysical, and redox properties, as well as their applications in organic electronics. We also present challenging synthetic targets, large BN- substituted polycyclic aromatics, such as regioregular BN heterosuperbenzenes, which can be viewed as BN-doped nanographenes. Finally, we propose an atomically precise bottom-up synthesis of structurally well-defined BN-doped graphenes. [ABSTRACT FROM AUTHOR]

Recently, many efforts have been devoted to developing novel polycyclic aromatics due to their unique optical and electronic properties and broad applications, such as in organic field-effect transistors, organic photovoltaics, and organic light-emitting diodes. Among various π-conjugated molecules, many truxene derivatives have interesting characteristics such as C3-symmetry, strong blue emission, and a planar rigid structure. Moreover, compared with many other π-conjugated aromatics, the synthesis and modification of truxene are particularly facile and diverse. In this account, we summarize investigations into truxene derivatives from synthesis and physical properties to applications in organic electronics. [ABSTRACT FROM AUTHOR]

Recently, polymer field-effect transistors have gone through rapid development. Nevertheless, charge transport mechanism and structure-property relationship are less understood. Here we use strong electron-deficient benzodifurandione-based poly( p-phenylene vinylene) ( BDPPV) as polymer backbone and develop six BDPPV-based polymers ( BDPPV-C1 to C6) with various side-chain branching positions to systematically study the side-chain effect on device performance. All the polymers exhibited ambient-stable n-type transporting behaviors with the highest electron mobility of up to 1.40 cm2 V−1 s−1. The film morphologies and microstructures of all the six polymers were systematically investigated. Our results demonstrate that the interchain π-π stacking distance decreases as moving the branching position away from polymer backbones, and an unprecedentedly close π-π stacking distance down to 3.38 Å is obtained for BDPPV-C4 to C6. Nonetheless, closer π-π stacking distance does not always correlate with higher electron mobility. Polymer crystallinity, thin film disorder, and polymer packing conformation, which all influenced by side-chain branching position, are proved to show significant influence on device performance. Our study not only reveals that π-π stacking distance is not the decisive factor on carrier mobility in conjugated polymers but also demonstrates that side-chain branching position engineering is a powerful strategy to modulate and balance these factors in conjugated polymers. [ABSTRACT FROM AUTHOR]

Boron–nitrogen units were incorporated into thiophene‐fused polycyclic aromatic compounds. Organic field‐effect transistors based on these azaborine compounds were fabricated, demonstrating a novel engineering concept of organic semiconductors and providing opportunities of a broad class of BN‐containing compounds for application in future organic electronic devices (see picture; μFET=hole mobility). [ABSTRACT FROM AUTHOR]

Two functional main-chain linear polyrotaxanes, one a covalent polymeric chain that threads through many macrocycles ( P1) and the other a poly[ n]rotaxane chain that is composed of many repeating rotaxane units ( P2), were synthesized by employing strong crown-ether/ammonium-based ( DB24C8/ DBA) host-guest interactions and click chemistry. Energy transfer between the wheel and axle units in both polyrotaxanes was used to provide insight into the conformational information of their resulting polyrotaxanes. Steady-state and time-resolved spectroscopy were performed to understand the conformation differences between polymers P1 and P2 in solution. Additional investigations by using dynamic/static light scattering and atomic force microscopy illustrated that polymer P1 was unbending and had a rigid rod-like structure, whilst polymer P2 was curved and flexible. This flexible topology facilitated the self-assembly of polymer P2 into relatively large ball-shaped particles. In addition, the energy transfer between the wheel and axle units was controlled by the addition of specific anions or base. The anion-induced energy enhancement was attributed to a change in electrostatic interactions between the polymer chains. The base-driven molecular shuttle broke the DB24C8/ DBA host-guest interactions. These results confirm that both intra- and intermolecular electrostatic interactions are crucial for modulating conformational topology, which determines the assembly of polyrotaxanes in solution. [ABSTRACT FROM AUTHOR]