330 results found
Heeney MJ, Marsh AV, Little M, et al., 2020, Highly deformed o-carborane-functionalised non-linear polycyclic aromatics with exceptionally long C-C bond lengths., Chemistry
The effect of substituting o-carborane into the most sterically hindered positions of phenanthrene and benzo(k)tetraphene is reported. Synthesised via a Bull-Hutchings-Quayle benzannulation, the crystal structures of these non-linear polycyclic aromatics exhibited the highest aromatic deformation parameters observed for any reported carborane compound to date, with the largest carboranyl C-C bond length of all organo-substituted o -carboranes. Photoluminescence studies of these compounds demonstrated efficient intramolecular charge-transfer, leading to aggregation induced emission properties. Additionally, an unusual low-energy excimer was observed for the phenanthryl compound. These are two new members of the family of carborane-functionalised non-linear polycyclic aromatics notable for their peculiar structures and multi-luminescent properties.
Tang Y, Bjuggren JM, Fei Z, et al., 2020, Origin of Open-Circuit Voltage Turnover in Organic Solar Cells at Low Temperature, SOLAR RRL, 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, [22.214.171.124]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.
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, Pages: e2000087-e2000087, 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.
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.
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
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
<p>Blade-coating is used to fabricate high hole mobility organic transistors based on a p-doped small-molecule:polymer blend semiconductor.</p>
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
Wu J, Luke J, Lee HKH, et al., 2019, Tail state limited photocurrent collection of thick photoactive layers in organic solar cells, Nature Communications, Vol: 10, ISSN: 2041-1723
Weanalyseorganic solar cells with four differentphotoactive blends exhibiting differing dependencies ofshort-circuit current upon photoactive layer thickness.These blends and devices are analysedbytransient optoelectronic techniques ofcarrier kinetics and densities, airphotoemission spectroscopyof material energetics, Kelvin probe measurements of work function, Mott-Schottky analyses of apparent doping density and by device modelling. We concludethat,for the device series studied, the photocurrent losswith thick active layersis primarilyassociatedwith the accumulation of photo-generated charge carriers in intra-bandgap tail states.This charge accumulation screens the device internal electricalfield, preventing efficient charge collection. Purification of one studied donor polymer is observed to reduce tail statedistribution anddensity and increase the maximal photoactive thickness forefficient operation. Ourwork suggests that selectingorganic photoactive layerswith a narrow distribution of tail states isa keyrequirement for the fabrication of efficient, high photocurrent, thick organic solar cells.
Lami V, Weu A, Zhang J, et al., 2019, Visualizing the Vertical Energetic Landscape in Organic Photovoltaics, JOULE, Vol: 3, Pages: 2513-2534, ISSN: 2542-4351
He Q, Shahid M, Wu J, et al., 2019, Fused Cyclopentadithienothiophene acceptor enables ultrahigh short‐circuit current and high efficiency >11% in as‐cast organic solar cells, Advanced Functional Materials, Vol: 29, Pages: 1-7, ISSN: 1616-301X
A new method to synthesize an electron‐rich building block cyclopentadithienothiophene (9H‐thieno‐[3,2‐b]thieno[2″,3″:4′,5′]thieno[2′,3′:3,4]cyclopenta[1,2‐d]thiophene, CDTT) via a facile aromatic extension strategy is reported. By combining CDTT with 1,1‐dicyanomethylene‐3‐indanone endgroups, a promising nonfullerene small molecule acceptor (CDTTIC) is prepared. As‐cast, single‐junction nonfullerene organic solar cells based on PFBDB‐T: CDTTIC blends exhibit very high short‐circuit currents up to 26.2 mA cm−2 in combination with power conversion efficiencies over 11% without any additional processing treatments. The high photocurrent results from the near‐infrared absorption of the CDTTIC acceptor and the well‐intermixed blend morphology of polymer donor PFBDB‐T and CDTTIC. This work demonstrates a useful fused ring extension strategy and promising solar cell results, indicating the great potential of the CDTT derivatives as electron‐rich building blocks for constructing high‐performance small molecule acceptors in organic solar cells.
Lin Y-H, Huang W, Pattanasattayavong P, et al., 2019, Deciphering photocarrier dynamics for tuneable high-performance perovskite-organic semiconductor heterojunction phototransistors, NATURE COMMUNICATIONS, Vol: 10, ISSN: 2041-1723
Jang S-Y, Kim I-B, Kang M, et al., 2019, Diseleno[3,2-b:2 ',3 '-d]selenophene-Containing High-Mobility Conjugated Polymer for Organic Field-Effect Transistors (vol 6, 1900245, 2019), ADVANCED SCIENCE, Vol: 6
Panidi J, Kainth J, Paterson AF, et al., 2019, Introducing a nonvolatile N-type dopant drastically improves electron transport in polymer and small-molecule organic transistors, Advanced Functional Materials, Vol: 29, Pages: 1-10, ISSN: 1616-301X
KGaA, Weinheim Molecular doping is a powerful yet challenging technique for enhancing charge transport in organic semiconductors (OSCs). While there is a wealth of research on p-type dopants, work on their n-type counterparts is comparatively limited. Here, reported is the previously unexplored n-dopant (12a,18a)-5,6,12,12a,13,18,18a,19-octahydro-5,6-dimethyl- 13,18[1′,2′]-benzenobisbenzimidazo [1,2-b:2′,1′-d]benzo[i][2.5]benzodiazo-cine potassium triflate adduct (DMBI-BDZC) and its application in organic thin-film transistors (OTFTs). Two different high electron mobility OSCs, namely, the polymer poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8- bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2′-bithiophene)] and a small-molecule naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) are used to study the effectiveness of DMBI-BDZC as a n-dopant. N-doping of both semiconductors results in OTFTs with improved electron mobility (up to 1.1 cm2 V−1 s−1), reduced threshold voltage and lower contact resistance. The impact of DMBI-BDZC incorporation is particularly evident in the temperature dependence of the electron transport, where a significant reduction in the activation energy due to trap deactivation is observed. Electron paramagnetic resonance measurements support the n-doping activity of DMBI-BDZC in both semiconductors. This finding is corroborated by density functional theory calculations, which highlights ground-state electron transfer as the main doping mechanism. The work highlights DMBI-BDZC as a promising n-type molecular dopant for OSCs and its application in OTFTs, solar cells, photodetectors, and thermoelectrics.
Musser AJ, Al-Hashimi M, Heeney M, et al., 2019, Heavy-atom effects on intramolecular singlet fission in a conjugated polymer, Journal of Chemical Physics, Vol: 151, ISSN: 0021-9606
A chief aim in singlet fission research is to develop new materials concepts for more efficient singlet fission. The typical approaches such as tuning π-overlap and charge-transfer interactions, enhancing delocalization, altering diradical character, or extending the conjugation length have profound effects simultaneously on the singlet and triplet energetics and the couplings between them. While these strategies have resulted in a handful of high-efficiency materials, the complex interplay of these factors makes systematic materials development challenging, and it would be useful to be able to selectively manipulate the properties and dynamics of just part of the singlet fission pathway. Here, we investigate the potential of heteroatom substitution as just such a selective tool. We explore the influence of heavy atoms within the main backbone of polythienylenevinylene and its selenophene and tellurophene derivatives. We find no significant effects on the prompt <300 fs intramolecular singlet fission dynamics but a clear heavy-atom effect on longer time scales.
Du T, Xu W, Daboczi M, et al., 2019, p-Doping of organic hole transport layers in p–i–n perovskite solar cells: correlating open-circuit voltage and photoluminescence quenching, Journal of Materials Chemistry A, Vol: 7, Pages: 18971-18979, ISSN: 2050-7488
Doping is a widely implemented strategy for enhancing the inherent electronic properties of charge transport layers in photovoltaic (PV) devices. Here, in direct contrast to existing understanding, we find that a reduction in p-doping of the organic hole transport layer (HTL) leads to substantial improvements in PV performance in planar p–i–n perovskite solar cells (PSCs), driven by improvements in open circuit voltage (VOC). Employing a range of transient and steady state characterisation tools, we find that the improvements of VOC correlate with reduced surface recombination losses in less p-doped HTLs. A simple device model including screening of bulk electric fields in the perovskite layer is used to explain this observation. In particular, photoluminescence (PL) emission of complete solar cells shows that efficient performance is correlated to a high PL intensity at open circuit and a low PL intensity at short circuit. We conclude that desirable transport layers for p–i–n PSCs should be charge selective contacts with low doping densities.
Choi HH, Paterson AF, Fusella MA, et al., 2019, Hall Effect in Polycrystalline Organic Semiconductors: The Effect of Grain Boundaries, ADVANCED FUNCTIONAL MATERIALS, ISSN: 1616-301X
Jang SY, Kim IB, Kang M, et al., 2019, Diseleno[3,2-b:2′,3′-d]selenophene-containing high-mobility conjugated polymer for organic field-effect transistors, Advanced Science, Vol: 6, ISSN: 2198-3844
KGaA, Weinheim The synthesis of a diseleno[3,2-b:2′,3′-d]selenophene (DSS) composed of three fused selenophenes is reported and it is used as a building block for the preparation of a high hole mobility conjugated polymer (PDSSTV). The polymer demonstrates strong intermolecular interactions even in solution, despite steric repulsion between the large Se atom in DSS and adjacent (C β )–H atoms which leads to a partially twisted confirmation PDSSTV. Nevertheless, 2D grazing incidence X-ray diffraction (2D-GIXD) analysis reveals that the polymer tends to align in a highly ordered edge-on orientation after thermal annealing. The polymer demonstrates promising performance in a field-effect transistor device with saturated hole mobility up to 2 cm 2 V −1 s −1 obtained under relatively low gate voltages of −30 V. The ultilization of a Se-containing fused aromatic system, therefore, appears to be a promising avenue for the development of high-performance conjugated polymers.
He Q, Shahid M, Panidi J, et al., 2019, A versatile star-shaped organic semiconductor based on benzodithiophene and diketopyrrolopyrrole, Journal of Materials Chemistry C, Vol: 7, Pages: 6622-6629, ISSN: 2050-7526
We report the synthesis of a new star-shaped π-conjugated oligomer, BDT(DPP)4, containing a benzodithiophene core and four diketopyrrolopyrrole arms. The thermal, electrochemical and optical properties are characterized and the results complemented by computational studies. The utility of the molecule is demonstrated in both solar cell and field-effect transistor devices. In the former, BDT(DPP)4 displays low efficiency when used as an acceptor in blends with poly(3-hexylthiophene) but exhibits promising performance as a donor, in blends with either a fullerene or a non-fullerene acceptor. In field-effect transistors BDT(DPP)4 exhibits typical p-type transistor behavior, which is in accordance with its better donor performance in solar cell devices.
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