Imperial College London

ProfessorMartinHeeney

Faculty of Natural SciencesDepartment of Chemistry

Professor of Organic Materials
 
 
 
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Contact

 

+44 (0)20 7594 1248m.heeney Website

 
 
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Location

 

401GMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

404 results found

Sharma A, AlGhamdi WS, Faber H, Lin Y-H, Liu C-H, Hsu E-K, Lin W-Z, Naphade D, Mandal S, Heeney M, Anthopoulos TDet al., 2023, Non-invasive, ultrasensitive detection of glucose in saliva using metal oxide transistors., Biosens Bioelectron, Vol: 237

Transistor-based biosensors represent an emerging technology for inexpensive point-of-care testing (POCT) applications. However, the limited sensitivity of the current transistor technologies hinders their practical deployment. In this study, we developed tri-channel In2O3/ZnO heterojunction thin-film transistors (TFTs) featuring the surface-immobilized enzyme glucose oxidase to detect glucose in various biofluids. This unusual channel design facilitates strong coupling between the electrons transported along the buried In2O3/ZnO heterointerface and the electrostatic perturbations caused by the interactions between glucose and surface-immobilized glucose oxidase. The enzyme selectively binds to glucose, causing a change in charge density on the channel surface. By exploring this effect, the solid-state biosensing TFT (BioTFT) can selectively detect glucose in artificial and real saliva over a wide range of concentrations from 500 nM to 20 mM with limits of detection of ∼365 pM (artificial saliva) and ∼416 nM (real saliva) in less than 60 s. The specificity of the sensor towards glucose has been demonstrated against various interfering species in artificial saliva, further highlighting its unique capabilities. Moreover, the BioTFTs exhibited good operating stability upon storage for up to two weeks, with relative standard deviation (RSD) values ranging from 2.36% to 6.39% for 500 nM glucose concentration. Our BioTFTs are easy to manufacture with reliable operation, making them ideal for non-invasive POCT applications.

Journal article

Ling Z, Nugraha MI, Hadmojo WT, Lin Y, Jeong SY, Yengel E, Faber H, Tang H, Laquai F, Emwas A-H, Chang X, Maksudov T, Gedda M, Woo HY, McCulloch I, Heeney M, Tsetseris L, Anthopoulos TDet al., 2023, Over 19% Efficiency in Ternary Organic Solar Cells Enabled by n-Type Dopants, ACS Energy Letters, Pages: 4104-4112, ISSN: 2380-8195

Journal article

Rimmele M, Qiao Z, Panidi J, Furlan F, Lee C, Tan WL, McNeill CR, Kim Y, Gasparini N, Heeney Met al., 2023, A polymer library enables the rapid identification of a highly scalable and efficient donor material for organic solar cells., Mater Horiz

The dramatic improvement of the PCE (power conversion efficiency) of organic photovoltaic devices in the past few years has been driven by the development of new polymer donor materials and non-fullerene acceptors (NFAs). In the design of such materials synthetic scalability is often not considered, and hence complicated synthetic protocols are typical for high-performing materials. Here we report an approach to readily introduce a variety of solubilizing groups into a benzo[c][1,2,5]thiadiazole acceptor comonomer. This allowed for the ready preparation of a library of eleven donor polymers of varying side chains and comonomers, which facilitated a rapid screening of properties and photovoltaic device performance. Donor FO6-T emerged as the optimal material, exhibiting good solubility in chlorinated and non-chlorinated solvents and achieving 15.4% PCE with L8BO as the acceptor (15.2% with Y6) and good device stability. FO6-T was readily prepared on the gram scale, and synthetic complexity (SC) analysis highlighted FO6-T as an attractive donor polymer for potential large scale applications.

Journal article

Ding B, Bhosale M, Bennett T, Heeney M, Plasser F, Esser B, Glöcklhofer Fet al., 2023, Reducing undesired solubility of squarephaneic tetraimide for use as an organic battery electrode material, Faraday Discussions, ISSN: 1359-6640

Locally aromatic alkyl-N-substituted squarephaneic tetraimide (SqTI) conjugated macrocycles are four-electron reducible, owing to global aromaticity and presumed global Baird aromaticity of the dianion and tetraanion states, respectively. However, their good solubility inhibits their application as a battery electrode material. By applying sidechain removal as a strategy to reduce SqTI solubility, we report the development of its unsubstituted derivative SqTI-H, which was obtained directly from squarephaneic tetraanhydride by facile treatment with hexamethyldisilazane and MeOH. Compared to alkyl-N-substituted SqTI-Rs, SqTI-H exhibited further improved thermal stability and low neutral state solubility in most common organic solvents, owing to computationally demonstrated hydrogen-bonding capabilities emanating from each imide position on SqTI-H. Reversible solid state electrochemical reduction of SqTI-H to the globally aromatic dianion state was also observed at -1.25 V vs. Fc/Fc+, which could be further reduced in two stages. Preliminary testing of SqTI-H in composite electrodes for lithium-organic half cells uncovered imperfect cycling performance, which may be explained by persistent solubility of reduced states, necessitating further optimisation of electrode fabrication procedures to attain maximum performance.

Journal article

He Q, Shaw J, Firdaus Y, Hu X, Ding B, Marsh AV, Dumon AS, Han Y, Fei Z, Anthopoulos TD, McNeill CR, Heeney Met al., 2023, p-Type Conjugated Polymers Containing Electron-Deficient Pentacyclic Azepinedione., Macromolecules, Vol: 56, Pages: 5825-5834, ISSN: 0024-9297

Bisthienoazepinedione (BTA) has been reported for constructing high-performing p-type conjugated polymers in organic electronics, but the ring extended version of BTA is not well explored. In this work, we report a new synthesis of a key building block to the ring expanded electron-deficient pentacyclic azepinedione (BTTA). Three copolymers of BTAA with benzodithiophene substituted by different side chains are prepared. These polymers exhibit similar energy levels and optical absorption in solution and solid state, while significant differences are revealed in their film morphologies and behavior in transistor and photovoltaic devices. The best-performing polymers in transistor devices contained alkylthienyl side chains on the BDT unit (pBDT-BTTA-2 and pBDT-BTTA-3) and demonstrated maximum saturation hole mobilities of 0.027 and 0.017 cm2 V-1 s-1. Blends of these polymers with PC71BM exhibited a best photovoltaic efficiency of 6.78% for pBDT-BTTA-3-based devices. Changing to a low band gap non-fullerene acceptor (BTP-eC9) resulted in improved efficiency of up to 13.5%. Our results are among the best device performances for BTA and BTTA-based p-type polymers and highlight the versatile applications of this electron-deficient BTTA unit.

Journal article

Cong S, Chen J, Ding B, Lan L, Wang Y, Chen C, Li Z, Heeney M, Yue Wet al., 2023, Tunable control of the performance of aqueous-based electrochemical devices by post-polymerization functionalization., Materials horizons, Vol: 10, Pages: 3090-3100, ISSN: 2051-6347

Functionalized polymeric mixed ionic-electronic conductors (PMIECs) are highly desired for the development of electrochemical applications, yet are hindered by the limited conventional synthesis techniques. Here, we propose a "graft-onto-polymer" synthesis strategy by post-polymerization functionalization (GOP-PPF) to prepare a family of PMIECs sharing the same backbone while functionalized with varying ethylene glycol (EG) compositions (two, four, and six EG repeating units). Unlike the typical procedure, GOP-PPF uses a nucleophilic aromatic substitution reaction for the facile and versatile attachment of functional units to a pre-synthesized conjugated-polymer precursor. Importantly, these redox-active PMIECs are investigated as a platform for energy storage devices and organic electrochemical transistors (OECTs) in aqueous media. The ion diffusivity, charge mobility and charge-storage capacity can be significantly improved by optimizing the EG composition. Specifically, g2T2-gBT6 containing the highest EG density gives the highest charge-storage capacity exceeding 180 F g-1 among the polymer series, resulting from the improved ion diffusivity. Moreover, g2T2-gBT4 with four EG repeating units exhibits a superior performance compared to its two analogues in OECTs, associated with a high μC* up to 359 F V-1 cm-1 s-1, owing to the optimal balance between ionic-electronic coupling and charge mobility. Through the GOP-PPF, PMIECs can be tailored to access desirable performance metrics at the molecular level.

Journal article

Panidi J, Mazzolini E, Eisner F, Fu Y, Furlan F, Qiao Z, Rimmele M, Li Z, Lu X, Nelson J, Durrant JR, Heeney M, Gasparini Net al., 2023, Biorenewable Solvents for High-Performance Organic Solar Cells., ACS Energy Lett, Vol: 8, Pages: 3038-3047, ISSN: 2380-8195

With the advent of nonfullerene acceptors (NFAs), organic photovoltaic (OPV) devices are now achieving high enough power conversion efficiencies (PCEs) for commercialization. However, these high performances rely on active layers processed from petroleum-based and toxic solvents, which are undesirable for mass manufacturing. Here, we demonstrate the use of biorenewable 2-methyltetrahydrofuran (2MeTHF) and cyclopentyl methyl ether (CPME) solvents to process donor: NFA-based OPVs with no additional additives in the active layer. Furthermore, to reduce the overall carbon footprint of the manufacturing cycle of the OPVs, we use polymeric donors that require a few synthetic steps for their synthesis, namely, PTQ10 and FO6-T, which are blended with the Y-series NFA Y12. High performance was achieved using 2MeTHF as the processing solvent, reaching PCEs of 14.5% and 11.4% for PTQ10:Y12 and FO6-T:Y12 blends, respectively. This work demonstrates the potential of using biorenewable solvents without additives for the processing of OPV active layers, opening the door to large-scale and green manufacturing of organic solar cells.

Journal article

Jiang Z, Du T, Lin C, Macdonald TJ, Chen J, Chin Y, Xu W, Ding B, Kim J, Durrant JR, Heeney M, McLachlan MAet al., 2023, Deciphering the role of hole transport layer HOMO level on the open circuit voltage of perovskite Solar cells, Advanced Materials Interfaces, Vol: 10, ISSN: 2196-7350

With the rapid development of perovskite solar cells, reducing losses in open-circuit voltage (Voc) is a key issue in efforts to further improve device performance. Here it is focused on investigating the correlation between the highest occupied molecular orbital (HOMO) of device hole transport layers (HTLs) and device Voc. To achieve this, structurally similar HTL materials with comparable optical band gaps and doping levels, but distinctly different HOMO levels are employed. Using light-intensity dependent Voc and photoluminescence measurements significant differences in the behavior of devices employing the two HTLs are highlighted. Light-induced increase of quasi-Fermi level splitting (ΔEF) in the perovskite layer results in interfacial quasi-Fermi level bending required to align with the HOMO level of the HTL, resulting in the Voc measured at the contacts being smaller than the ΔEF in the perovskite. It is concluded that minimizing the energetic offset between HTLs and the perovskite active layer is of great importance to reduce non-radiative recombination losses in perovskite solar cells with high Voc values that approach the radiative limit.

Journal article

Bennett TLR, Marsh AV, Turner JM, Plasser F, Heeney M, Glöcklhofer Fet al., 2023, Functionalisation of conjugated macrocycles with type I and II concealed antiaromaticity via cross-coupling reactions, Molecular Systems Design & Engineering, Vol: 8, Pages: 713-720, ISSN: 2058-9689

Conjugated macrocycles can exhibit concealed antiaromaticity; that is, despite not being antiaromatic, under specific circumstances, they can display properties typically observed in antiaromatic molecules due to their formal macrocyclic 4n π-electron system. Paracyclophanetetraene (PCT) and its derivatives are prime examples of macrocycles exhibiting this behaviour. In redox reactions and upon photoexcitation, they have been shown to behave like antiaromatic molecules (requiring type I and II concealed antiaromaticity, respectively), with such phenomena showing potential for use in battery electrode materials and other electronic applications. However, further exploration of PCTs has been hindered by the lack of halogenated molecular building blocks that would permit their integration into larger conjugated molecules by cross-coupling reactions. Here, we present two dibrominated PCTs, obtained as a mixture of regioisomers from a three-step synthesis, and demonstrate their functionalisation via Suzuki cross-coupling reactions. Optical, electrochemical, and theoretical studies reveal that aryl substituents can subtly tune the properties and behaviour of PCT, showing that this is a viable strategy in further exploring this promising class of materials.

Journal article

Jacoutot P, Scaccabarozzi A, Nodari D, Panidi J, Qiao Z, Schiza A, Nega A, Dimitrakopoulou-Strauss A, Gregoriou V, Heeney M, Chochos C, Bakulin A, Gasparini Net al., 2023, Enhanced Sub-1 eV detection in organic photodetectors through tuning polymer energetics and microstructure, Science Advances, Vol: 9, Pages: 1-9, ISSN: 2375-2548

One of the key challenges facing organic photodiodes (OPD) is increasing the detection into the IR region. Organic semiconductor polymers provide a platform for tuning the bandgap and optoelectronic response to go beyond the traditional 1000 nm benchmark. In this work, we present a NIR polymer with absorption up to 1500 nm. The polymer-based OPD delivers a high specific detectivity D* of 1.03×1010 Jones (-2 V) at 1200 nm and a dark current Jd of just 2.3×10-6 A cm-2 at -2V. We demonstrate a strong improvement of all OPD metrics in the NIR region compared to previously reported NIR-OPD, due to the enhanced crystallinity and optimized energy alignment which leads to reduced charge recombination. The high D* value in the 1100-1300 nm region is particularly promising for biosensing applications. We demonstrate the OPD as a pulse oximeter under NIR illumination, delivering heart rate and blood oxygen saturation readings in real-time without signal amplification.

Journal article

Polak DW, Andrews I, Farrow G, Musser AJ, Auty A, Chekulaev D, Weinstein JA, Heeney M, Clark Jet al., 2023, Conjugation-length dependence of regioregular oligo 3-alkyl(thienylene-vinylene)s demonstrates polyene-like behaviour with weak electron-electron correlations., Phys Chem Chem Phys, Vol: 25, Pages: 11205-11215

Poly(3-alkyl(thienylene-vinylene)) (P3TV) and its longer oligomers have negligibly low photoluminescence quantum yields, however, the reason for their low yields is currently debated. Here, we prepare a series of regioregular (3-dodecyl)thienylene-vinylene oligomers with n = 2-8 repeat units by iterative Horner-Wadsworth-Emmons reactions, and report their steady-state, transient absorption, and emission spectroscopy. The results presented here demonstrate that 3-alkyl(thienylene-vinylene) oligomers form part of the polyene family. The shortest (n = 2) oligomer emits from the bright 1Bu state, while fluorescence in oligomers with n = 3, 4 is from the formally dark 2Ag state, allowed via Herzberg-Teller vibronic coupling to the nearby bright 1Bu state as described for diphenyl-polyenes. Longer oligomers and the polymer are essentially non-emissive as the 2Ag state can no longer intensity-borrow from the 1Bu state. We demonstrate that the spectral shapes, photoluminescence quantum yield, and transient spectral behaviour can all be explained using a polyene model with weak electronic correlations.

Journal article

Ding B, Jo I-Y, Yu H, Kim JH, Marsh AV, Gutiérrez-Fernández E, Ramos N, Rapley CL, Rimmele M, He Q, Martín J, Gasparini N, Nelson J, Yoon M-H, Heeney Met al., 2023, Enhanced Organic Electrochemical Transistor Performance of Donor-Acceptor Conjugated Polymers Modified with Hybrid Glycol/Ionic Side Chains by Postpolymerization Modification., Chem Mater, Vol: 35, Pages: 3290-3299, ISSN: 0897-4756

Emergent bioelectronic technologies are underpinned by the organic electrochemical transistor (OECT), which employs an electrolyte medium to modulate the conductivity of its organic semiconductor channel. Here we utilize postpolymerization modification (PPM) on a conjugated polymer backbone to directly introduce glycolated or anionic side chains via fluoride displacement. The resulting polymers demonstrated increased volumetric capacitances, with subdued swelling, compared to their parent polymer in p-type enhancement mode OECTs. This increase in capacitance was attributed to their modified side chain configurations enabling cationic charge compensation for thin film electrochemical oxidation, as deduced from electrochemical quartz crystal microbalance measurements. An overall improvement in OECT performance was recorded for the hybrid glycol/ionic polymer compared to the parent, owing to its low swelling and bimodal crystalline orientation as imaged by grazing-incidence wide-angle X-ray scattering, enabling its high charge mobility at 1.02 cm2·V-1·s-1. Compromised device performance was recorded for the fully glycolated derivative compared to the parent, which was linked to its limited face-on stacking, which hindered OECT charge mobility at 0.26 cm2·V-1·s-1, despite its high capacitance. These results highlight the effectiveness of anionic side chain attachment by PPM as a means of increasing the volumetric capacitance of p-type conjugated polymers for OECTs, while retaining solid-state macromolecular properties that facilitate hole transport.

Journal article

Anies F, Furlan F, Qiao Z, Pirela V, Bidwell M, Rimmele M, Martin J, Gasparini N, Heeney Met al., 2023, A comparison of para, meta, and ortho-carborane centred non-fullerene acceptors for organic solar cells, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 11, Pages: 3989-3996, ISSN: 2050-7526

Journal article

Creamer A, Lo Fiego A, Agliano A, Prados Martin L, Hogset H, Najer A, Richards D, Wojciechowski J, Foote J, Kim N, Monahan A, Tang J, Shamsabadi A, Rochet LNC, Thanasi IA, de la Ballina LR, Rapley CL, Turnock S, Love EA, Bugeon L, Dallman MJ, Heeney M, Kramer-Marek G, Chudasama V, Fenaroli F, Stevens Met al., 2023, Modular synthesis of semiconducting graft co-polymers to achieve ‘clickable’ fluorescent nanoparticles with long circulation and specific cancer targeting, Advanced Materials, Pages: 1-14, ISSN: 0935-9648

Semiconducting polymer nanoparticles (SPNs) are explored for applications in cancer theranostics because of their high absorption coefficients, photostability, and biocompatibility. However, SPNs are susceptible to aggregation and protein fouling in physiological conditions, which can be detrimental for in vivo applications. Here, a method for achieving colloidally stable and low-fouling SPNs is described by grafting poly(ethylene glycol) (PEG) onto the backbone of the fluorescent semiconducting polymer, poly(9,9′-dioctylfluorene-5-fluoro-2,1,3-benzothiadiazole), in a simple one-step substitution reaction, postpolymerization. Further, by utilizing azide-functionalized PEG, anti-human epidermal growth factor receptor 2 (HER2) antibodies, antibody fragments, or affibodies are site-specifically “clicked” onto the SPN surface, which allows the functionalized SPNs to specifically target HER2-positive cancer cells. In vivo, the PEGylated SPNs are found to have excellent circulation efficiencies in zebrafish embryos for up to seven days postinjection. SPNs functionalized with affibodies are then shown to be able to target HER2 expressing cancer cells in a zebrafish xenograft model. The covalent PEGylated SPN system described herein shows great potential for cancer theranostics.

Journal article

He Q, Basu A, Cha H, Daboczi M, Panidi J, Tan L, Hu X, Huang CC, Ding B, White AJP, Kim J-S, Durrant JR, Anthopoulos TD, Heeney Met al., 2023, Ultra-Narrowband Near-Infrared Responsive J-Aggregates of Fused Quinoidal Tetracyanoindacenodithiophene, ADVANCED MATERIALS, ISSN: 0935-9648

Journal article

Anies F, Nugraha MI, Fall A, Panidi J, Zhao Y, Vanelle P, Tsetseris L, Broggi J, Anthopoulos TD, Heeney Met al., 2023, In Situ Generation of n-Type Dopants by Thermal Decarboxylation, ADVANCED FUNCTIONAL MATERIALS, ISSN: 1616-301X

Journal article

Hu X, Basu A, Rimmele M, Marsh AVV, Anies F, He Q, Anthopoulos TDD, Heeney Met al., 2022, N-type polymer semiconductors incorporating heteroannulated benzothiadiazole, POLYMER CHEMISTRY, Vol: 14, Pages: 469-476, ISSN: 1759-9954

Journal article

Marsh AV, Heeney M, 2022, Conjugated polymers based on selenophene building blocks, POLYMER JOURNAL, ISSN: 0032-3896

Journal article

Eder S, Ding B, Thornton DB, Sammut D, White AJP, Plasser F, Stephens IEL, Heeney M, Mezzavilla S, Glöcklhofer Fet al., 2022, Squarephaneic tetraanhydride: a conjugated square‐shaped cyclophane for the synthesis of porous organic materials, Angewandte Chemie International Edition, Vol: 61, Pages: 1-8, ISSN: 1433-7851

Aromatic carboxylic anhydrides are ubiquitous building blocks in organic materials chemistry and have received considerable attention in the synthesis of organic semiconductors, pigments, and battery electrode materials. Here we extend the family of aromatic carboxylic anhydrides with a unique new member, a conjugated cyclophane with four anhydride groups. The cyclophane is obtained in a three-step synthesis and can be functionalised efficiently, as shown by the conversion into tetraimides and an octacarboxylate. Crystal structures reveal the high degree of porosity achievable with the new building block. Excellent electrochemical properties and reversible reduction to the tetraanions are shown for the imides; NMR and EPR measurements confirm the global aromaticity of the dianions and evidence the global Baird aromaticity of the tetraanions. Considering the short synthesis and unique properties, we expect widespread use of the new building block in the development of organic materials.

Journal article

He Q, Kafourou P, Hu X, Heeney Met al., 2022, Development of non-fullerene electron acceptors for efficient organic photovoltaics, SN Applied Sciences, Vol: 4, ISSN: 2523-3971

Compared to fullerene based electron acceptors, n-type organic semiconductors, so-called non-fullerene acceptors (NFAs), possess some distinct advantages, such as readily tuning of optical absorption and electronic energy levels, strong absorption in the visible region and good morphological stability for flexible electronic devices. The design and synthesis of new NFAs have enabled the power conversion efficiencies (PCEs) of organic photovoltaic (OPV) devices to increase to around 19%. This review summarises the important breakthroughs that have contributed to this progress, focusing on three classes of NFAs, i.e. perylene diimide (PDI), diketopyrrolopyrrole (DPP) and acceptor–donor–acceptor (A-D-A) based NFAs. Specifically, the PCEs of PDI, DPP, and A-D-A series based non-fullerene OPVs have been reported up to 11%, 13% and 19%, respectively. Structure–property relationships of representative NFAs and their impact on OPV performances are discussed. Finally, we consider the remaining challenges and promising directions for achieving high-performing NFAs.

Journal article

Rimmele M, Glöcklhofer F, Heeney M, 2022, Post-polymerisation approaches for the rapid modification of conjugated polymer properties., Materials Horizons, Vol: 9, Pages: 2678-2697, ISSN: 2051-6355

Post-polymerisation functionalisation provides a facile and efficient way for the introduction of functional groups on the backbone of conjugated polymers. Using post-polymerisation functionalisation approaches, the polymer chain length is usually not affected, meaning that the resulting polymers only differ in their attached functional groups or side chains, which makes them particularly interesting for investigating the influence of the different groups on the polymer properties. For such functionalisations, highly efficient and selective reactions are needed to avoid the formation of complex mixtures or permanent defects in the polymer backbone. A variety of suitable synthetic approaches and reactions that fulfil these criteria have been identified and reported. In this review, a thorough overview is given of the post-polymerisation functionalisations reported to date, with the methods grouped based on the type of reaction used: cycloaddition, oxidation/reduction, nucleophilic aromatic substitution, or halogenation and subsequent cross-coupling reaction. Instead of modifications on the aliphatic side chains of the conjugated polymers, we focus on modifications directly on the conjugated backbones, as these have the most pronounced effect on the optical and electronic properties. Some of the discussed materials have been used in applications, ranging from solar cells to bioelectronics. By providing an overview of this versatile and expanding field for the first time, we showcase post-polymerisation functionalisation as an exciting pathway for the creation of new conjugated materials for a range of applications.

Journal article

Jang S-Y, Kim I-B, Kim Y, Lim D-H, Kang H, Heeney M, Kim D-Yet al., 2022, Facile direct C-H arylation polymerization of conjugated polymer, PDCBT, for organic solar cells, Macromolecular Rapid Communications, ISSN: 1022-1336

Direct arylation polymerization (DArP) is a synthetic method for conjugated polymers; in DArP, organometallic functionalization steps are omitted and there are no toxic byproducts. As a result, it is considered a more sustainable alternative compared to conventional methods such as Stille polymerization. To explore the possibility of DArP-based polymers as donor materials in organic solar cells (OSCs), a series of conjugated polymers based on the structure of PDCBT (poly[2,2''''-bis[[(2-butyloctyl)oxy]carbonyl][2,2':5',2'':5'',2'''-quaterthiophene]-5,5'''-diyl]) are synthesized using DArP and Stille polymerization. By controlling the monomer concentration and reaction time in DArP, DArP-5 with the highest Mn (21.9 kDa) can be obtained and its optoelectronic properties, electrochemical properties, and microscopic molecular ordering are comparable to those of Stille-based PDCBT (Stille-P). Analysis of the polymer structure indicates no structural defects such as crosslinking from undesired β-coupling reactions in DArP-5. Upon blending with the PC71BM acceptor molecule, an increase in the crystallite size of DArP-5 is also observed. In OSC devices with a polymer:PC71BM bulk-heterojunction photoactive layer, DArP-5 demonstrates a comparable power conversion efficiency of 5.8% with that of Stille-P (5.5%). These results prove that DArP is suitable for synthesizing PDCBT, and DArP-based PDCBT can be used in OSCs as an alternative of Stille-based one.

Journal article

Kafourou P, Qiao Z, Toth M, Anies F, Eisner F, Gasparini N, Heeney Met al., 2022, Low Dark Current Organic Photodetectors Utilizing Highly Cyanated Non-fullerene Acceptors, ACS APPLIED MATERIALS & INTERFACES, ISSN: 1944-8244

Journal article

Polak DW, do Casal MT, Toldo JM, Hu X, Amoruso G, Pomeranc O, Heeney M, Barbatti M, Ashfold MNR, Oliver TAAet al., 2022, Probing the electronic structure and photophysics of thiophene-diketopyrrolopyrrole derivatives in solution, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 24, Pages: 20138-20151, ISSN: 1463-9076

Journal article

Rotas G, Antoniou G, Papagiorgis P, Basu A, Panidi J, Ufimkin P, Tsetseris L, Itskos G, Heeney M, Vougioukalakis GC, Anthopoulos TD, Keivanidis PEet al., 2022, Doping-induced decomposition of organic semiconductors: a caveat to the use of Lewis acid p-dopants, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 10, Pages: 12751-12764, ISSN: 2050-7526

Journal article

Zhang C, Tan WL, Liu Z, He Q, Li Y, Ma J, Chesman ASR, Han Y, McNeill CR, Heeney M, Fei Zet al., 2022, High-Performance Unipolar n-Type Conjugated Polymers Enabled by Highly Electron-Deficient Building Blocks Containing F and CN Groups (vol 55, pg 4429, 2022), MACROMOLECULES, Vol: 55, Pages: 6295-6295, ISSN: 0024-9297

Journal article

Dou F, Fei Z, Buchaca-Domingo E, Brosseau C-N, Leonelli R, Heeney M, Zhang Xet al., 2022, Observing the On-Site Generation of Excitons and Charges by Low- Temperature Spectroscopy, ACS APPLIED MATERIALS & INTERFACES, ISSN: 1944-8244

Journal article

Nugraha MI, Gedda M, Firdaus Y, Scaccabarozzi AD, Zhang W, Alshammari S, Anies F, Adilbekova B, Emwas A-H, McCulloch I, Heeney M, Tsetseris L, Anthopoulos TDet al., 2022, Addition of diquat enhances the electron mobility in various non-fullerene acceptor molecules, Advanced Functional Materials, ISSN: 1616-301X

Molecular doping of organic semiconductors is often used to enhance their charge transport characteristics. Despite its success, however, most studies to date concern p-doping with considerably fewer reports involving n-dopants. Here, n-doping of organic thin-film transistors (OTFTs) based on several non-fullerene acceptor (NFA) molecules using the recently developed diquat (DQ) as a soluble molecular dopant is reported. The low ionization potential of DQ facilitates efficient electron transfer and subsequent n-doping of the NFAs, resulting in a consistent increase in the electron field-effect mobility. Solution-processed BTP-eC9 and N3-based OTFTs exhibit significant increase in the electron mobility upon DQ doping, with values increasing from 0.02 to 0.17 cm2 V–1 s–1 and from 0.2 to 0.57 cm2 V–1 s–1, respectively. A remarkable electron mobility of >1 cm2 V–1 s–1 is achieved for O-IDTBR transistors upon optimal doping with DQ. The enhanced performance originates primarily from synergistic effects on electronic transport and changes in morphology, including: i) significant reduction of contact resistances, ii) formation of larger crystalline domains, iii) change of preferred crystal orientation, and iv) alteration in molecular packing motif. This work demonstrates the universality of DQ as an electronic additive for improving electron transport in OTFTs.

Journal article

Hu X, Datt R, He Q, Kafourou P, Ka Hin Lee H, White AJP, Tsoi WC, Heeney Met al., 2022, Facile synthesis of annulated benzothiadiazole derivatives and their application as medium band gap acceptors in organic photovoltaic devices, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 10, Pages: 9249-9256, ISSN: 2050-7526

Journal article

Zhang C, Tan WL, Liu Z, He Q, Li Y, Ma J, Chesman ASR, Han Y, McNeill CR, Heeney M, Fei Zet al., 2022, High-Performance Unipolar n-Type Conjugated Polymers Enabled by Highly Electron-Deficient Building Blocks Containing F and CN Groups, MACROMOLECULES, ISSN: 0024-9297

Journal article

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