Academic Appointments


Professional Education


  • Ph.D., Imperial College London, Polymer Chemistry (2020)
  • MSci, Imperial College London, Chemistry (2016)

All Publications


  • The hierarchical structure of organic mixed ionic-electronic conductors and its evolution in water. Nature materials Tsarfati, Y., Bustillo, K. C., Savitzky, B. H., Balhorn, L., Quill, T. J., Marks, A., Donohue, J., Zeltmann, S. E., Takacs, C. J., Giovannitti, A., McCulloch, I., Ophus, C., Minor, A. M., Salleo, A. 2024

    Abstract

    Polymeric organic mixed ionic-electronic conductors underpin several technologies in which their electrochemical properties are desirable. These properties, however, depend on the microstructure that develops in their aqueous operational environment. We investigated the structure of a model organic mixed ionic-electronic conductor across multiple length scales using cryogenic four-dimensional scanning transmission electron microscopy in both its dry and hydrated states. Four-dimensional scanning transmission electron microscopy allows us to identify the prevalent defects in the polymer crystalline regions and to analyse the liquid crystalline nature of the polymer. The orientation maps of the dry and hydrated polymers show that swelling-induced disorder is mostly localized in discrete regions, thereby largely preserving the liquid crystalline order. Therefore, the liquid crystalline mesostructure makes electronic transport robust to electrolyte ingress. This study demonstrates that cryogenic four-dimensional scanning transmission electron microscopy provides multiscale structural insights into complex, hierarchical structures such as polymeric organic mixed ionic-electronic conductors, even in their hydrated operating state.

    View details for DOI 10.1038/s41563-024-02016-6

    View details for PubMedID 39333273

    View details for PubMedCentralID 4991841

  • The Role Of Side Chains and Hydration on Mixed Charge Transport in N-Type Polymer Films. Advanced materials (Deerfield Beach, Fla.) Surgailis, J., Flagg, L. Q., Richter, L. J., Druet, V., Griggs, S., Wu, X., Moro, S., Ohayon, D., Kousseff, C. J., Marks, A., Maria, I. P., Chen, H., Moser, M., Costantini, G., McCulloch, I., Inal, S. 2024: e2313121

    Abstract

    Introducing ethylene glycol (EG) side chains to a conjugated polymer backbone is a well-established synthetic strategy for designing organic mixed ion-electron conductors (OMIECs). However, the impact that film swelling has on mixed conduction properties has yet to be scoped, particularly for electron-transporting (n-type) OMIECs. Here, we investigate the effect of the length of branched EG chains on mixed charge transport of n-type OMIECs based on a naphthalene-1,4,5,8-tetracarboxylic-diimide-bithiophene backbone. We use atomic force microscopy, grazing-incidence wide-angle X-ray scattering (GIWAXS), and scanning tunneling microscopy to establish the similarities between the common-backbone films in dry conditions. Electrochemical quartz crystal microbalance with dissipation monitori1ng (EQCM-D) and in situ GIWAXS measurements reveal stark changes in film swelling properties and microstructure during electrochemical doping, depending on the side chain length. We find that even in the loss of the crystallite content upon contact with the aqueous electrolyte, the films can effectively transport charges and that it is rather the high water content that harms the electronic interconnectivity within the OMIEC films. These results highlight the importance of controlling water uptake in the films to impede the charge transport in n-type electrochemical devices. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202313121

    View details for PubMedID 38554042

  • Enhancement of Conjugated Polymer Microstructure and Mixed-Conducting Properties via Chalcogenophene Heteroatom Substitution CHEMISTRY OF MATERIALS Paulsen, B. D., Meli, D., Moser, M., Marks, A., Ponder Jr, J. F., Wu, R., Schafer, E. A., Strzalka, J., Zhang, Q., Mcculloch, I., Rivnay, J. 2024
  • Charge Carrier Induced Structural Ordering And Disordering in Organic Mixed Ionic Electronic Conductors. Advanced materials (Deerfield Beach, Fla.) Quill, T. J., LeCroy, G., Marks, A., Hesse, S. A., Thiburce, Q., McCulloch, I., Tassone, C. J., Takacs, C. J., Giovannitti, A., Salleo, A. 2024: e2310157

    Abstract

    Operational stability underpins the successful application of organic mixed ionic-electronic conductors (OMIECs) in a wide range of fields, including biosensing, neuromorphic computing, and wearable electronics. In this work, we investigate both the operation and stability of a p-type OMIEC material of various molecular weights. Electrochemical transistor measurements reveal that device operation is very stable for at least 300 charging/discharging cycles independent of molecular weight, provided the charge density is kept below the threshold where strong charge-charge interactions become likely. When electrochemically charged to higher charge densities, we observe an increase in device hysteresis and a decrease in conductivity due to a drop in the hole mobility arising from long-range microstructural disruptions. By employing operando X-ray scattering techniques, we find two regimes of polaron-induced structural changes: 1) polaron-induced structural ordering at low carrier densities, and 2) irreversible structural disordering that disrupts charge transport at high carrier densities, where charge-charge interactions are significant. These operando measurements also reveal that the transfer curve hysteresis at high carrier densities is accompanied by an analogous structural hysteresis, providing a microstructural basis for such instabilities. This work provides a mechanistic understanding of the structural dynamics and material instabilities of OMIEC materials during device operation. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202310157

    View details for PubMedID 38198654

  • Origins of hydrogen peroxide selectivity during oxygen reduction on organic mixed ionic-electronic conducting polymers ENERGY & ENVIRONMENTAL SCIENCE Duran, A., Liang, A., Denti, I., Yu, H., Pearce, D., Marks, A., Penn, E., Treiber, J., Weaver, K., Turaski, L., Maria, I. P., Griggs, S., Chen, X., Salleo, A., Chueh, W. C., Nelson, J., Giovannitti, A., Mefford, J. 2023

    View details for DOI 10.1039/d3ee02102e

    View details for Web of Science ID 001119466200001

  • On the Importance of Chemical Precision in Organic Electronics: Fullerene Intercalation in Perfectly Alternating Conjugated Polymers ADVANCED FUNCTIONAL MATERIALS Vanderspikken, J., Liu, Z., Wu, X., Beckers, O., Moro, S., Quill, T., Liu, Q., Goossens, A., Marks, A., Weaver, K., Hamid, M., Goderis, B., Nies, E., Lemaur, V., Beljonne, D., Salleo, A., Lutsen, L., Vandewal, K., Van Mele, B., Costantini, G., Van den Brande, N., Maes, W. 2023
  • Volumetric Electron Transfer from Metabolites to Chemically Doped Polymer Electrodes ADVANCED FUNCTIONAL MATERIALS Tan, S., Lee, G., Rozylowicz, K., Marks, A., Salleo, A. 2023
  • An ordered, self-assembled nanocomposite with efficient electronic and ionic transport. Nature materials Quill, T. J., LeCroy, G., Halat, D. M., Sheelamanthula, R., Marks, A., Grundy, L. S., McCulloch, I., Reimer, J. A., Balsara, N. P., Giovannitti, A., Salleo, A., Takacs, C. J. 2023

    Abstract

    Mixed conductors-materials that can efficiently conduct both ionic and electronic species-are an important class of functional solids. Here we demonstrate an organic nanocomposite that spontaneously forms when mixing an organic semiconductor with an ionic liquid and exhibits efficient room-temperature mixed conduction. We use a polymer known to form a semicrystalline microstructure to template ion intercalation into the side-chain domains of the crystallites, which leaves electronic transport pathways intact. Thus, the resulting material is ordered, exhibiting alternating layers of rigid semiconducting sheets and soft ion-conducting layers. This unique dual-network microstructure leads to a dynamic ionic/electronic nanocomposite with liquid-like ionic transport and highly mobile electronic charges. Using a combination of operando X-ray scattering and in situ spectroscopy, we confirm the ordered structure of the nanocomposite and uncover the mechanisms that give rise to efficient electron transport. These results provide fundamental insights into charge transport in organic semiconductors, as well as suggesting a pathway towards future improvements in these nanocomposites.

    View details for DOI 10.1038/s41563-023-01476-6

    View details for PubMedID 36797383

  • 2D metal-organic frameworks for ultraflexible electrochemical transistors with high transconductance and fast response speeds SCIENCE ADVANCES Song, J., Liu, H., Zhao, Z., Guo, X., Liu, C., Griggs, S., Marks, A., Zhu, Y., Law, H., McCulloch, I., Yan, F. 2023; 9 (2): eadd9627

    Abstract

    Electrochemical transistors (ECTs) have shown broad applications in bioelectronics and neuromorphic devices due to their high transconductance, low working voltage, and versatile device design. To further improve the device performance, semiconductor materials with both high carrier mobilities and large capacitances in electrolytes are needed. Here, we demonstrate ECTs based on highly oriented two-dimensional conjugated metal-organic frameworks (2D c-MOFs). The ion-conductive vertical nanopores formed within the 2D c-MOFs films lead to the most convenient ion transfer in the bulk and high volumetric capacitance, endowing the devices with fast speeds and ultrahigh transconductance. Ultraflexible device arrays are successfully used for wearable on-skin recording of electrocardiogram (ECG) signals along different directions, which can provide various waveforms comparable with those of multilead ECG measurement systems for monitoring heart conditions. These results indicate that 2D c-MOFs are excellent semiconductor materials for high-performance ECTs with promising applications in flexible and wearable electronics.

    View details for DOI 10.1126/sciadv.add9627

    View details for Web of Science ID 000911464300028

    View details for PubMedID 36630506

    View details for PubMedCentralID PMC9833676

  • The effect of residual palladium on the performance of organic electrochemical transistors. Nature communications Griggs, S., Marks, A., Meli, D., Rebetez, G., Bardagot, O., Paulsen, B. D., Chen, H., Weaver, K., Nugraha, M. I., Schafer, E. A., Tropp, J., Aitchison, C. M., Anthopoulos, T. D., Banerji, N., Rivnay, J., McCulloch, I. 2022; 13 (1): 7964

    Abstract

    Organic electrochemical transistors are a promising technology for bioelectronic devices, with applications in neuromorphic computing and healthcare. The active component enabling an organic electrochemical transistor is the organic mixed ionic-electronic conductor whose optimization is critical for realizing high-performing devices. In this study, the influence of purity and molecular weight is examined for a p-type polythiophene and an n-type naphthalene diimide-based polymer in improving the performance and safety of organic electrochemical transistors. Our preparative GPC purification reduced the Pd content in the polymers and improved their organic electrochemical transistor mobility by ~60% and 80% for the p- and n-type materials, respectively. These findings demonstrate the paramount importance of removing residual Pd, which was concluded to be more critical than optimization of a polymer's molecular weight, to improve organic electrochemical transistor performance and that there is readily available improvement in performance and stability of many of the reported organic mixed ionic-electronic conductors.

    View details for DOI 10.1038/s41467-022-35573-y

    View details for PubMedID 36575179

  • Conjugated polymers for microwave applications: untethered sensing platforms and multifunctional devices. Advanced materials (Deerfield Beach, Fla.) Tan, S. T., Giovannitti, A., Marks, A., Moser, M., Quill, T. J., McCulloch, I., Salleo, A., Bonacchini, G. E. 2022: e2202994

    Abstract

    In the past two decades, organic electronic materials have enabled and accelerated a large and diverse set of technologies, from energy harvesting devices and electro-mechanical actuators, to flexible and printed (opto)electronic circuitry. Among organic (semi)conductors, mixed ionic-electron conductors (OMIECs) are now at the center of renewed interest in organic electronics, as they are key drivers of recent developments in the fields of bioelectronics, energy storage, and neuromorphic computing. However, due to the relatively slow switching dynamics of organic electronics, their application in microwave technology, until recently, has been overlooked. Nonetheless, other unique properties of OMIECs, such as their substantial electrochemical tunability, charge modulation range and processability, make this field of use ripe with opportunities. In this work, we demonstrate the use of a series of solution-processed intrinsic OMIECs to actively tune the properties of metamaterial-inspired microwave devices, including an untethered bioelectrochemical sensing platform that requires no external power, and a tunable resonating structure with independent amplitude- and frequency-modulation. These devices showcase the considerable potential of OMIEC-based metadevices in autonomous bioelectronics and reconfigurable microwave optics. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202202994

    View details for PubMedID 35759573

  • Tuning Organic Electrochemical Transistor Threshold Voltage using Chemically Doped Polymer Gates. Advanced materials (Deerfield Beach, Fla.) Tan, S. T., Lee, G., Denti, I., LeCroy, G., Rozylowicz, K., Marks, A., Griggs, S., McCulloch, I., Giovannitti, A., Salleo, A. 2022: e2202359

    Abstract

    Organic electrochemical transistors (OECTs) have shown promise as transducers and amplifiers of minute electronic potentials due to their large transconductances. Tuning OECT threshold voltage is important to achieve low-powered devices with amplification properties within the desired operational voltage range. However, traditional design approaches have struggled to decouple channel and materials properties from threshold voltage, thereby compromising on several other OECT performance metrics such as electrochemical stability, transconductance, and dynamic range. In this work, we utilize simple solution processing methods to chemically dope polymer gate electrodes, thereby controlling their work function, which in turn tunes the operation voltage range of OECTs without perturbing their channel properties. Chemical doping of initially air-sensitive polymer electrodes further improves their electrochemical stability in ambient conditions. Thus, we demonstrate, for the first time, OECTs which are simultaneously low-powered and electrochemically resistant to oxidative side reactions at ambient conditions. This approach shows that threshold voltage, which was once interwoven with other OECT properties, can in fact be an independent design parameter, expanding the design space of OECTs. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202202359

    View details for PubMedID 35737653

  • Synthetic Nuances to Maximize n-Type Organic Electrochemical Transistor and Thermoelectric Performance in Fused Lactam Polymers. Journal of the American Chemical Society Marks, A., Chen, X., Wu, R., Rashid, R. B., Jin, W., Paulsen, B. D., Moser, M., Ji, X., Griggs, S., Meli, D., Wu, X., Bristow, H., Strzalka, J., Gasparini, N., Costantini, G., Fabiano, S., Rivnay, J., McCulloch, I. 2022

    Abstract

    A series of fully fused n-type mixed conduction lactam polymers p(g7NCnN), systematically increasing the alkyl side chain content, are synthesized via an inexpensive, nontoxic, precious-metal-free aldol polycondensation. Employing these polymers as channel materials in organic electrochemical transistors (OECTs) affords state-of-the-art n-type performance with p(g7NC10N) recording an OECT electron mobility of 1.20 * 10-2 cm2 V-1 s-1 and a muC* figure of merit of 1.83 F cm-1 V-1 s-1. In parallel to high OECT performance, upon solution doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI), the highest thermoelectric performance is observed for p(g7NC4N), with a maximum electrical conductivity of 7.67 S cm-1 and a power factor of 10.4 muW m-1 K-2. These results are among the highest reported for n-type polymers. Importantly, while this series of fused polylactam organic mixed ionic-electronic conductors (OMIECs) highlights that synthetic molecular design strategies to bolster OECT performance can be translated to also achieve high organic thermoelectric (OTE) performance, a nuanced synthetic approach must be used to optimize performance. Herein, we outline the performance metrics and provide new insights into the molecular design guidelines for the next generation of high-performance n-type materials for mixed conduction applications, presenting for the first time the results of a single polymer series within both OECT and OTE applications.

    View details for DOI 10.1021/jacs.2c00735

    View details for PubMedID 35257589

  • Organic Electrochemical Transistors: An Emerging Technology for Biosensing ADVANCED MATERIALS INTERFACES Marks, A., Griggs, S., Gasparini, N., Moser, M. 2022
  • The effect of side chain engineering on conjugated polymers in organic electrochemical transistors for bioelectronic applications JOURNAL OF MATERIALS CHEMISTRY C He, Y., Kukhta, N. A., Marks, A., Luscombe, C. K. 2022

    View details for DOI 10.1039/d1tc05229b

    View details for Web of Science ID 000739864000001

  • Propylene and butylene glycol: new alternatives to ethylene glycol in conjugated polymers for bioelectronic applications MATERIALS HORIZONS Moser, M., Wang, Y., Hidalgo, T., Liao, H., Yu, Y., Chen, J., Duan, J., Moruzzi, F., Griggs, S., Marks, A., Gasparini, N., Wadsworth, A., Inal, S., McCulloch, I., Yue, W. 2021

    Abstract

    To date, many of the high-performance conjugated polymers employed as OECT channel materials make use of ethylene glycol (EG) chains to confer the materials with mixed ionic-electronic conduction properties, with limited emphasis placed on alternative hydrophilic moieties. While a degree of hydrophilicity is required to facilitate some ionic conduction in hydrated channels, an excess results in excessive swelling, with potentially detrimental effects on charge transport. This is therefore a subtle balance that must be optimised to maximise electrical performance. Herein a series of polymers based on a bithiophene-thienothiophene conjugated backbone was synthesised and the conventional EG chains substituted by their propylene and butylene counterparts. Specifically, the use of propylene and butylene chains was found to afford polymers with a more hydrophobic character, thereby reducing excessive water uptake during OECT operation and in turn significantly boosting the polymers' electronic charge carrier mobility. Despite the polymers' lower water uptake, the newly developed oligoether chains retained sufficiently high degrees of hydrophilicity to enable bulk volumetric doping, ultimately resulting in the development of polymers with superior OECT performance.

    View details for DOI 10.1039/d1mh01889b

    View details for Web of Science ID 000732832900001

    View details for PubMedID 34935815

  • Molecular Design Strategies toward Improvement of Charge Injection and Ionic Conduction in Organic Mixed Ionic-Electronic Conductors for Organic Electrochemical Transistors. Chemical reviews Kukhta, N. A., Marks, A., Luscombe, C. K. 1800

    Abstract

    Expanding the toolbox of the biology and electronics mutual conjunction is a primary aim of bioelectronics. The organic electrochemical transistor (OECT) has undeniably become a predominant device for mixed conduction materials, offering impressive transconduction properties alongside a relatively simple device architecture. In this review, we focus on the discussion of recent material developments in the area of mixed conductors for bioelectronic applications by means of thorough structure-property investigation and analysis of current challenges. Fundamental operation principles of the OECT are revisited, and characterization methods are highlighted. Current bioelectronic applications of organic mixed ionic-electronic conductors (OMIECs) are underlined. Challenges in the performance and operational stability of OECT channel materials as well as potential strategies for mitigating them, are discussed. This is further expanded to sketch a synopsis of the history of mixed conduction materials for both p- and n-type channel operation, detailing the synthetic challenges and milestones which have been overcome to frequently produce higher performing OECT devices. The cumulative work of multiple research groups is summarized, and synthetic design strategies are extracted to present a series of design principles that can be utilized to drive figure-of-merit performance values even further for future OMIEC materials.

    View details for DOI 10.1021/acs.chemrev.1c00266

    View details for PubMedID 34902244

  • n-Type organic semiconducting polymers: stability limitations, design considerations and applications JOURNAL OF MATERIALS CHEMISTRY C Griggs, S., Marks, A., Bristow, H., McCulloch, I. 2021; 9 (26): 8099-8128

    Abstract

    This review outlines the design strategies which aim to develop high performing n-type materials in the fields of organic thin film transistors (OTFT), organic electrochemical transistors (OECT) and organic thermoelectrics (OTE). Figures of merit for each application and the limitations in obtaining these are set out, and the challenges with achieving consistent and comparable measurements are addressed. We present a thorough discussion of the limitations of n-type materials, particularly their ambient operational instability, and suggest synthetic methods to overcome these. This instability originates from the oxidation of the negative polaron of the organic semiconductor (OSC) by water and oxygen, the potentials of which commonly fall within the electrochemical window of n-type OSCs, and consequently require a LUMO level deeper than ∼-4 eV for a material with ambient stability. Recent high performing n-type materials are detailed for each application and their design principles are discussed to explain how synthetic modifications can enhance performance. This can be achieved through a number of strategies, including utilising an electron deficient acceptor-acceptor backbone repeat unit motif, introducing electron-withdrawing groups or heteroatoms, rigidification and planarisation of the polymer backbone and through increasing the conjugation length. By studying the fundamental synthetic design principles which have been employed to date, this review highlights a path to the development of promising polymers for n-type OSC applications in the future.

    View details for DOI 10.1039/d1tc02048j

    View details for Web of Science ID 000661565300001

    View details for PubMedID 34277009

    View details for PubMedCentralID PMC8264852

  • n-Type Rigid Semiconducting Polymers Bearing Oligo(Ethylene Glycol) Side Chains for High-Performance Organic Electrochemical Transistors ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Chen, X., Marks, A., Paulsen, B. D., Wu, R., Rashid, R. B., Chen, H., Alsufyani, M., Rivnay, J., McCulloch, I. 2021; 60 (17): 9368-9373

    Abstract

    N-type conjugated polymers as the semiconducting component of organic electrochemical transistors (OECTs) are still undeveloped with respect to their p-type counterparts. Herein, we report two rigid n-type conjugated polymers bearing oligo(ethylene glycol) (OEG) side chains, PgNaN and PgNgN, which demonstrated an essentially torsion-free π-conjugated backbone. The planarity and electron-deficient rigid structures enable the resulting polymers to achieve high electron mobility in an OECT device of up to the 10-3  cm2  V-1  s-1 range, with a deep-lying LUMO energy level lower than -4.0 eV. Prominently, the polymers exhibited a high device performance with a maximum dimensionally normalized transconductance of 0.212 S cm-1 and the product of charge-carrier mobility μ and volumetric capacitance C* of 0.662±0.113 F cm-1  V-1  s-1 , which are among the highest in n-type conjugated polymers reported to date. Moreover, the polymers are synthesized via a metal-free aldol-condensation polymerization, which is beneficial to their application in bioelectronics.

    View details for DOI 10.1002/anie.202013998

    View details for Web of Science ID 000627845300001

    View details for PubMedID 33368944

  • Reversible Electrochemical Charging of n-Type Conjugated Polymer Electrodes in Aqueous Electrolytes. Journal of the American Chemical Society Szumska, A. A., Maria, I. P., Flagg, L. Q., Savva, A., Surgailis, J., Paulsen, B. D., Moia, D., Chen, X., Griggs, S., Mefford, J. T., Rashid, R. B., Marks, A., Inal, S., Ginger, D. S., Giovannitti, A., Nelson, J. 2021

    Abstract

    Conjugated polymers achieve redox activity in electrochemical devices by combining redox-active, electronically conducting backbones with ion-transporting side chains that can be tuned for different electrolytes. In aqueous electrolytes, redox activity can be accomplished by attaching hydrophilic side chains to the polymer backbone, which enables ionic transport and allows volumetric charging of polymer electrodes. While this approach has been beneficial for achieving fast electrochemical charging in aqueous solutions, little is known about the relationship between water uptake by the polymers during electrochemical charging and the stability and redox potentials of the electrodes, particularly for electron-transporting conjugated polymers. We find that excessive water uptake during the electrochemical charging of polymer electrodes harms the reversibility of electrochemical processes and results in irreversible swelling of the polymer. We show that small changes of the side chain composition can significantly increase the reversibility of the redox behavior of the materials in aqueous electrolytes, improving the capacity of the polymer by more than one order of magnitude. Finally, we show that tuning the local environment of the redox-active polymer by attaching hydrophilic side chains can help to reach high fractions of the theoretical capacity for single-phase electrodes in aqueous electrolytes. Our work shows the importance of chemical design strategies for achieving high electrochemical stability for conjugated polymers in aqueous electrolytes.

    View details for DOI 10.1021/jacs.1c06713

    View details for PubMedID 34469688

  • O-17 NMR spectroscopy as a tool to study hydrogen bonding of cholesterol in lipid bilayers CHEMICAL COMMUNICATIONS Rowlands, L. J., Marks, A., Sanderson, J. M., Law, R. 2020; 56 (92): 14499-14502

    Abstract

    Cholesterol is a crucial component of biological membranes and can interact with other membrane components through hydrogen bonding. NMR spectroscopy has been used previously to investigate this bonding, however this study represents the first 17O NMR spectroscopy study of isotopically enriched cholesterol. We demonstrate the 17O chemical shift is dependent on hydrogen bonding, providing a novel method for the study of cholesterol in bilayers.

    View details for DOI 10.1039/d0cc05466f

    View details for Web of Science ID 000591568400037

    View details for PubMedID 33150883

  • Polaron Delocalization in Donor-Acceptor Polymers and its Impact on Organic Electrochemical Transistor Performance. Angewandte Chemie (International ed. in English) Moser, M. n., Savva, A. n., Thorley, K. n., Paulsen, B. D., Hidalgo, T. C., Ohayon, D. n., Chen, H. n., Giovannitti, A. n., Marks, A. n., Gasparini, N. n., Wadsworth, A. n., Rivnay, J. n., Inal, S. n., McCulloch, I. n. 2020

    Abstract

    Donor-acceptor (D-A) polymers are promising materials for organic electrochemical transistors (OECTs), as they minimize detrimental faradaic side-reactions during OECT operation, yet their steady-state OECT performance still lags far behind their all-donor counterparts. Here, we report three D-A polymers based on the diketopyrrolopyrrole unit that afford OECT performances similar to those of all-donor polymers, hence representing a significant improvement to the previously developed D-A copolymers. In addition to improved OECT performance, DFT simulations of the polymers and their respective hole polarons also revealed a positive correlation between hole polaron delocalization and steady-state OECT performance, providing new insights into the design of OECT materials. More importantly, we demonstrate how polaron delocalization can be tuned directly at the molecular level by selection of the building blocks comprising the polymers' conjugated backbone, thus paving the way for the development of even higher performing OECT polymers.

    View details for DOI 10.1002/anie.202014078

    View details for PubMedID 33259685

  • Polaron spin dynamics in high-mobility polymeric semiconductors NATURE PHYSICS Schott, S., Chopra, U., Lemaur, V., Melnyk, A., Olivier, Y., Di Pietro, R., Romanov, I., Carey, R. L., Jiao, X., Jellett, C., Little, M., Marks, A., McNeill, C. R., McCulloch, I., McNellis, E. R., Andrienko, D., Beljonne, D., Sinova, J., Sirringhaus, H. 2019; 15 (8): 814-+
  • Long spin diffusion lengths in doped conjugated polymers due to enhanced exchange coupling (vol 2, pg 98, 2019) NATURE ELECTRONICS Wang, S., Venkateshvaran, D., Mahani, M. R., Chopra, U., McNellis, E. R., Di Pietro, R., Schott, S., Wittmann, A., Schweicher, G., Cubukcu, M., Kang, K., Carey, R., Wagner, T. J., Siebrecht, J. M., Wong, D. H., Jacobs, I. E., Aboljadayel, R. O., Ionescu, A., Egorov, S. A., Mueller, S., Zadvorna, O., Skalski, P., Jellett, C., Little, M., Marks, A., McCulloch, I., Wunderlich, J., Sinova, J., Sirringhaus, H. 2019; 2 (7): 313
  • Critical review of the molecular design progress in non-fullerene electron acceptors towards commercially viable organic solar cells CHEMICAL SOCIETY REVIEWS Wadsworth, A., Moser, M., Marks, A., Little, M. S., Gasparini, N., Brabec, C. J., Baran, D., McCulloch, I. 2019; 48 (6): 1596-1625

    Abstract

    Fullerenes have formed an integral part of high performance organic solar cells over the last 20 years, however their inherent limitations in terms of synthetic flexibility, cost and stability have acted as a motivation to develop replacements; the so-called non-fullerene electron acceptors. A rapid evolution of such materials has taken place over the last few years, yielding a number of promising candidates that can exceed the device performance of fullerenes and provide opportunities to improve upon the stability and processability of organic solar cells. In this review we explore the structure-property relationships of a library of non-fullerene acceptors, highlighting the important chemical modifications that have led to progress in the field and provide an outlook for future innovations in electron acceptors for use in organic photovoltaics.

    View details for DOI 10.1039/c7cs00892a

    View details for Web of Science ID 000462633900004

    View details for PubMedID 29697109

  • Crystal Engineering of Dibenzothiophenothieno[3,2-b]thiophene (DBTTT) Isomers for Organic Field-Effect Transistors CHEMISTRY OF MATERIALS Chen, H., Schweicher, G., Planells, M., Ryno, S. M., Broch, K., White, A. P., Simatos, D., Little, M., Jellett, C., Cryer, S. J., Marks, A., Hurhangee, M., Bredas, J., Sirringhaus, H., McCulloch, I. 2018; 30 (21): 7587-7592