341 results found
Rimmele M, Nogala W, Seif-Eddine M, et al., 2021, Functional group introduction and aromatic unit variation in a set of π‑conjugated macrocycles: revealing the central role of local and global aromaticity, Organic Chemistry Frontiers, ISSN: 2052-4110
π-Conjugated macrocycles are molecules with unique properties that are increasingly exploited for applications and the question of whether they can sustain global aromatic or antiaromatic ring currents is particularly intriguing. However, there are only a small number of experimental studies that investigate how the properties of π‑conjugated macrocycles evolve with systematic structural changes. Here, we present such a systematic experimental study of a set of [184.108.40.206]cyclophanetetraenes, all with formally Hückel antiaromatic ground states, and combine it with an in-depth computational analysis. The study reveals the central role of local and global aromaticity for rationalizing the observed optoelectronic properties, ranging from extremely large Stokes shifts of up to 1.6 eV to reversible fourfold reduction, a highly useful feature for charge storage/accumulation applications. A recently developed method for the visualization of chemical shielding tensors (VIST) is applied to provide unique insight into local and global ring currents occurring in different planes along the macrocycle. Conformational changes as a result of the structural variations can further explain some of the observations. The study contributes to the development of structure–property relationships and molecular design guidelines and will help to understand, rationalize, and predict the properties of other π‑conjugated macrocycles.
Yoo D-J, Heeney M, Glocklhofer F, et al., 2021, Tetradiketone macrocycle for divalent aluminium ion batteries, Nature Communications, Vol: 12, Pages: 1-9, ISSN: 2041-1723
Contrary to early motivation, the majority of aluminium ion batteries developed to date do not utilise multivalent ion storage; rather, these batteries rely on monovalent complex ions for their main redox reaction. This limitation is somewhat frustrating because the innate advantages of metallic aluminium such as its low cost and high air stability cannot be fully taken advantage of. Here, we report a tetradiketone macrocycle as an aluminium ion battery cathode material that reversibly reacts with divalent (AlCl2+) ions and consequently achieves a high specific capacity of 350 mAh g−1 along with a lifetime of 8000 cycles. The preferred storage of divalent ions over their competing monovalent counterparts can be explained by the relatively unstable discharge state when using monovalent AlCl2+ ions, which exert a moderate resonance effect to stabilise the structure. This study opens an avenue to realise truly multivalent aluminium ion batteries based on organic active materials, by tuning the relative stability of discharged states with carrier ions of different valence states.
Paterson AF, Li R, Markina A, et al., 2021, N-Doping improves charge transport and morphology in the organic non-fullerene acceptor O-IDTBR dagger, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 9, Pages: 4486-4495, ISSN: 2050-7526
Adamczak D, Perinot A, Komber H, et al., 2021, Influence of synthetic pathway, molecular weight and side chains on properties of indacenodithiophene-benzothiadiazole copolymers made by direct arylation polycondensation, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 9, Pages: 4597-4606, ISSN: 2050-7526
Heeney M, Kafourou P, Park B, et al., 2021, One-step six-fold cyanation of benzothiadiazole acceptor Units for air-stable high-performance n-type organic field-effect transistors, Angewandte Chemie International Edition, Vol: 60, Pages: 5970-5977, ISSN: 1433-7851
We report a new high electron affinity acceptor end group for organic semiconductors, 2,1,3-benzothiadiazole-4,5,6-tricarbonitrile (TCNBT). An n-type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a six-fold nucleophilic substitution with cyanides on a fluorinated precursor, itself prepared by a direct arylation approach. This one-step chemical modification was found to significantly impact the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n-type semiconductor. The highly electron-deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n-type organic field-effect transistors (OFETs). Solution-processed OFETs based on TCNBT IDT exhibited a charge carrier mobility of up to µ e ≈ 0.15 cm 2 V -1 s -1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.
Kafourou P, Park B, Luke J, et al., 2021, One‐step sixfold cyanation of benzothiadiazole acceptor units for air‐stable high‐performance n‐type organic field‐effect transistors, Angewandte Chemie, Vol: 133, Pages: 6035-6042, ISSN: 0044-8249
Reported here is a new high electron affinity acceptor end group for organic semiconductors, 2,1,3‐benzothiadiazole‐4,5,6‐tricarbonitrile (TCNBT). An n‐type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a sixfold nucleophilic substitution with cyanide on a fluorinated precursor, itself prepared by a direct arylation approach. This one‐step chemical modification significantly impacted the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n‐type semiconductor. The electron‐deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n‐type organic field‐effect transistors (OFETs). Solution‐processed OFETs based on TCNBT IDT exhibited a charge‐carrier mobility of up to μe≈0.15 cm2 V−1 s−1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.
Hodsden T, Thorley KJ, Basu A, et al., 2021, The influence of alkyl group regiochemistry and backbone fluorination on the packing and transistor performance of N-cyanoimine functionalised indacenodithiophenes, Materials Advances, Vol: 2, Pages: 1706-1714
The synthesis of two novel n-type molecular organic semiconductors based on a fluorinated indacenodithiophene core in combination with an electron withdrawing N-cyanoimine group is reported, and the influence of the regiochemistry of the solubilizing sidechain is investigated. The N-cyanoimine is confirmed to be a strongly electron accepting group, which in combination with the core fluorination resulted in high electron affinities for both materials. Single crystal analysis demonstrated that whilst both materials arrange in ordered slipped stacks with close π–π stacking distances (∼3.40 Å), significant differences in electron transfer integrals for the two regioisomers were observed, relating to differences in relative molecular displacement along the π-stacking direction. Organic thin-film transistors fabricated via blade-coating displayed electron mobility up to 0.13 cm2 V−1 s−1 for the isomer with the larger transfer integral.
Rodriguez-Martinez X, Pascual-San-Jose E, Fei Z, et al., 2021, Predicting the photocurrent-composition dependence in organic solar cells, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 14, Pages: 986-994, ISSN: 1754-5692
Marsh AV, Little M, Cheetham NJ, et al., 2020, Highly Deformed o-Carborane Functionalised Non-linear Polycyclic Aromatics with Exceptionally Long C-C Bonds, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 27, Pages: 1970-1975, ISSN: 0947-6539
Lin Y, Nugraha MI, Firdaus Y, et al., 2020, A Simple n-Dopant Derived from Diquat Boosts the Efficiency of Organic Solar Cells to 18.3%, ACS ENERGY LETTERS, Vol: 5, Pages: 3663-3671, ISSN: 2380-8195
Basu A, Niazi MR, Scaccabarozzi AD, et al., 2020, Impact of p-type doping on charge transport in blade-coated small-molecule:polymer blend transistors, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 8, Pages: 15368-15376, ISSN: 2050-7526
He Q, Eisner FD, Pearce D, et al., 2020, Ring fusion in tetrathienylethene cored perylene diimide tetramers affords acceptors with strong and broad absorption in the near-UV to visible region, Journal of Materials Chemistry C, Vol: 8, Pages: 17237-17244, ISSN: 2050-7526
In this work, we designed and synthesized two novel perylene diimide (PDI) tetramers based on a tetrathienylethene core, named TTE-PDI4 and FTTE-PDI4, and investigated their application as non-fullerene acceptors for organic photovoltaics. The free rotation of PDIs and adjacent thiophene units renders TTE-PDI4 with a highly twisted molecular geometry. The ring fusion of TTE-PDI4 yields FTTE-PDI4, a more rigid molecule with increased intramolecular stacking. Interestingly, TTE-PDI4 and FTTE-PDI4 possess similar energy levels but very different UV-Vis absorptions, with the latter showing strong broad-band absorption with multiple sharp peaks in the 300–600 nm region. Through time-dependent density functional theory (TD-DFT) calculations, we show that this broad absorption spectrum in FTTE-PDI4 arises from the combination of multiple bright transitions in the visible region with a strong vibronic progression, tentatively assigned to the dominant C[double bond, length as m-dash]C stretching mode. TTE-PDI4, despite having a lower energy absorption onset, shows weaker absorption at long wavelengths. Due to its higher absorption as well as its increased rigidity, FTTE-PDI4 shows a higher photocurrent and hence a higher power conversion efficiency (PCE), of 6.6%, when blended with the polymer donor PFBDB-T than TTE-PDI4 based blends (PCE of 3.8%). The greater rigidity of FTTE-PDI4 is likely to contribute to the good fill factor of the blend devices. Potential for further improvement through reducing voltage losses is identified.
Cong S, Creamer A, Fei Z, et al., 2020, Tunable control of the hydrophilicity and wettability of conjugated polymers by a postpolymerization modification approach., Macromolecular Bioscience, Vol: 20, Pages: 1-8, ISSN: 1616-5187
A facile method to prepare hydrophilic polymers by a postpolymerization nucleophillic aromatic substitution reaction of fluoride on an emissive conjugated polymer (CP) backbone is reported. Quantitative functionalization by a series of monofunctionalized ethylene glycol oligomers, from dimer to hexamer, as well as with high molecular weight polyethylene glycol is demonstrated. The length of the ethylene glycol sidechains is shown to have a direct impact on the surface wettability of the polymer, as well as its solubility in polar solvents. However, the energetics and band gap of the CPs remain essentially constant. This method therefore allows an easy way to modulate the wettability and solubility of CP materials for a diverse series of applications.
Tang Y, Bjuggren JM, Fei Z, et al., 2020, Origin of Open-Circuit Voltage Turnover in Organic Solar Cells at Low Temperature, SOLAR RRL, Vol: 4, ISSN: 2367-198X
Scaccabarozzi AD, Scuratti F, Barker AJ, et al., 2020, Understanding charge transport in high-mobilityp-doped multicomponent blend organic transistors, Advanced Electronic Materials, Pages: 1-9, ISSN: 2199-160X
The use of ternary systems comprising polymers, small molecules, and molecular dopants represents a promising approach for the development of high‐mobility, solution‐processed organic transistors. However, the current understanding of the charge transport in these complex systems, and particularly the role of molecular doping, is rather limited. Here, the role of the individual components in enhancing hole transport in the best‐performing ternary blend systems comprising the small molecule 2,7‐dioctylbenzothieno[3,2‐b]benzothiophene (C8‐BTBT), the conjugated polymer indacenodithiophene‐alt‐benzothiadiazole (C16IDT‐BT), and the molecular p‐type dopant (C60F48) is investigated. Temperature‐dependent charge transport measurements reveal different charge transport regimes depending on the blend composition, crossing from a thermally activated to a band‐like behavior. Using the charge‐modulation spectroscopy technique, it is shown that in the case of the pristine blend, holes relax onto the conjugated polymer phase where shallow traps dominate carrier transport. Addition of a small amount of C60F48 deactivates those shallow traps allowing for a higher degree of hole delocalization within the highly crystalline C8‐BTBT domains located on the upper surface of the blend film. Such synergistic effect of a highly ordered C8‐BTBT phase, a polymer bridging grain boundaries, and p‐doping results in the exceptionally high hole mobilities and band‐like transport observed in this blend system.
Wang S, Shaw J, Han Y, et al., 2020, Multibranched aliphatic side chains for π-conjugated polymers with a high density of ‘unshielded’ aromatics, Chemical Communications, Vol: 56, Pages: 12138-12141, ISSN: 1359-7345
Strongly solubilising multibranched aliphatic side chains for π-conjugated polymers are reported, enabling soluble polymers with a high density of unsubstituted, ‘unshielded’ aromatics.
Zhang D, Heeney M, 2020, Organic Donor-Acceptor Systems, ASIAN JOURNAL OF ORGANIC CHEMISTRY, Vol: 9, Pages: 1251-1251, ISSN: 2193-5807
Green JP, Dai H, Anies F, et al., 2020, Functional 4H-Dithieno[3,2-b:2 ',3 '-d]pyrrole Derivatives in Base-Dopable Conjugated Polymers and Oligomers, MACROMOLECULES, Vol: 53, Pages: 6649-6655, ISSN: 0024-9297
Anies F, Wang S, Hodsden T, et al., 2020, A Structurally Simple but High-Performing Donor-Acceptor Polymer for Field-Effect Transistor Applications, ADVANCED ELECTRONIC MATERIALS, Vol: 6, ISSN: 2199-160X
Eder S, Yoo D-J, Nogala W, et al., 2020, Switching between local and global aromaticity in a conjugated macrocycle for high-performance organic sodium-ion battery anodes, Angewandte Chemie International Edition, Vol: 59, Pages: 12958-12964, ISSN: 1433-7851
Aromatic organic compounds can be used as electrode materials in rechargeable batteries and are expected to advance the development of both anode and cathode materials for sodium-ion batteries (SIBs). However, most aromatic organic compounds assessed as anode materials in SIBs to date exhibit significant degradation issues under fast-charge/discharge conditions and unsatisfying long-term cycling performance. Now, a molecular design concept is presented for improving the stability of organic compounds for battery electrodes. The molecular design of the investigated compound, [220.127.116.11]paracyclophane-1,9,17,25-tetraene (PCT), can stabilize the neutral state by local aromaticity and the doubly reduced state by global aromaticity, resulting in an anode material with extraordinarily stable cycling performance and outstanding performance under fast-charge/discharge conditions, demonstrating an exciting new path for the development of electrode materials for SIBs and other types of batteries.
Guo D, Li L, Zhu X, et al., 2020, Naphthalene diimide based near-infrared luminogens with aggregation-induced emission characteristics for biological imaging and high mobility ambipolar transistors, SCIENCE CHINA-CHEMISTRY, Vol: 63, Pages: 1198-1207, ISSN: 1674-7291
Marsh A, Dyson MJ, Cheetham NJ, et al., 2020, Correlating the Structural and Photophysical Properties ofOrtho,Meta, andPara-Carboranyl-Anthracene Dyads, ADVANCED ELECTRONIC MATERIALS, Vol: 6, ISSN: 2199-160X
Meindl B, Pfennigbauer K, Stöger B, et al., 2020, Double ring-closing approach for the synthesis of 2,3,6,7-substituted anthracene derivatives., Journal of Organic Chemistry, Vol: 85, Pages: 8240-8244, ISSN: 0022-3263
A method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain, is presented. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable, protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions, followed by a deprotection and intramolecular double ring-closing condensation reaction.
Lin Y-H, Huang W, Pattanasattayavong P, et al., 2020, Deciphering photocarrier dynamics for tuneable high-performance perovskite-organic semiconductor heterojunction phototransistors (vol 10, 4475, 2019), NATURE COMMUNICATIONS, Vol: 11, ISSN: 2041-1723
Hodsden T, Thorley KJ, Panidi J, et al., 2020, Core fluorination enhances solubility and ambient stability of an IDT‐based n‐type semiconductor in transistor devices, Advanced Functional Materials, Vol: 30, Pages: 1-12, ISSN: 1616-301X
The synthesis of a novel fluorinated n‐type small molecule based on an indacenodithiophene core is reported. Fluorination is found to have a significant impact on the physical properties, including a surprisingly dramatic improvement in solubility, in addition to effectively stabilizing the lowest‐unoccupied molecular orbital energy (−4.24 eV). Single‐crystal analysis and density functional theory calculations indicate the improved solubility can be attributed to backbone torsion resulting from the positioning of the fluorine group in close proximity to the strongly electron‐withdrawing dicyanomethylene group. Organic thin‐film transistors made via blade coating display high electron mobility (up to 0.49 cm2 V−1 s−1) along with good retention of performance in ambient conditions.
Meindl B, Pfennigbauer K, Stöger B, et al., 2020, Double ring-closing approach for the synthesis of 2,3,6,7-substituted anthracene derivatives, Publisher: ChemRxiv
<jats:p>Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br></jats:p>
He Q, Shahid M, Jiao X, et al., 2020, The crucial role of fluorine in fully alkylated ladder type carbazole based non-fullerene organic solar cells, ACS Applied Materials and Interfaces, Vol: 12, Pages: 9555-9562, ISSN: 1944-8244
Two fused ladder type non-fullerene acceptors, DTCCIC and DTCCIC-4F, based on an electron-donating alkylated dithienocyclopentacarbazole core flanked by electron-withdrawing non-fluorinated or fluorinated 1,1-dicyanomethylene-3-indanone (IC or IC-4F), are prepared and utilized in organic solar cells (OSCs). The two new molecules reveal planar structures and strong aggregation behavior, and fluorination is shown to red shift the optical band gap and down shift energy levels. OSCs based on DTCCIC-4F exhibit a power conversion efficiency of 12.6 %, much higher than that of DTCCIC based devices (6.2 %). Microstructural studies reveal that while both acceptors are highly crystalline, bulk heterojunction blends based on the non-fluorinated DTCCIC result in overly coarse domains, while blends based on the fluorinated DTCCIC-4F exhibit a more optimal nanoscale morphology. These results highlight the importance of end group fluorination in controlling molecular aggregation and miscibility.
Firdaus Y, He Q, Lin Y, et al., 2020, Novel wide-bandgap non-fullerene acceptors for efficient tandem organic solar cells, 10th International Conference on Materials for Advanced Technologies (ICMAT) / Symposium P on Advanced Inorganic Materials and Thin Film Technology for Solar Energy Harvesting and Electronic Application, Publisher: ROYAL SOC CHEMISTRY, Pages: 1164-1175, ISSN: 2050-7488
Leventis A, Chmovzh TN, Knyazeva EA, et al., 2020, A novel low-bandgap pyridazine thiadiazole-based conjugated polymer with deep molecular orbital levels, POLYMER CHEMISTRY, Vol: 11, Pages: 581-585, ISSN: 1759-9954
Chaudhry MU, Panidi J, Nam S, et al., 2019, Polymer Light-Emitting Transistors With Charge-Carrier Mobilities Exceeding 1 cm(2) V-1 s(-1), ADVANCED ELECTRONIC MATERIALS, Vol: 6, ISSN: 2199-160X
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