ORCID Profile
0000-0002-6340-7217
Current Organisations
Imperial College London
,
King Abdullah University of Science and Technology
,
King Abdullah University of Science and Technology (KAUST)
,
University of Oxford
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Publications
Separate charge transport pathways determined by the time of flight method in bimodal polytriarylamine
Publisher: AIP Publishing
Date: 2009
DOI: 10.1063/1.3054180
Abstract: Time of flight photocurrent transient studies on thin films of bimodal polytriarylamine (PTAA) show two distinct and separate arrival times for hole transport in the same s le at a single field. The corresponding mobilities differ by two orders of magnitude, typically μfast∼10−3 cm2 V−1 s−1 and μslow∼10−5 cm2 V−1 s−1 at room temperature, and are measured parametric in electric field and temperature. The mobility data are analyzed using the correlated disorder model by Novikov, yielding a fitting parameter set. The two conduction paths are believed to come about as a result of phase segregation between the shorter and longer polymer chains with the shorter chains giving rise to the faster conduction pathways (as confirmed by results obtained for monomodal, shorter, and longer chain PTAA, by s le thickness scaling of the photocurrents and by reversal of the illuminated electrode). Separate arrival times are also obtained in a blend of the two short and long chain monomodal polymers. The phase separation within the film is inferred by the appearance of two glass transition temperatures using dynamic mechanical thermal analysis.
Thieno[3,2-b]thiophene−Diketopyrrolopyrrole-Containing Polymers for High-Performance Organic Field-Effect Transistors and Organic Photovoltaic Devices
Publisher: American Chemical Society (ACS)
Date: 18-02-2011
DOI: 10.1021/JA110619K
Abstract: We report the synthesis and polymerization of a novel thieno[3,2-b]thiophene-diketopyrrolopyrrole-based monomer. Copolymerization with thiophene afforded a polymer with a maximum hole mobility of 1.95 cm(2) V(-1) s(-1), which is the highest mobility from a polymer-based OFET reported to date. Bulk-heterojunction solar cells comprising this polymer and PC(71)BM gave a power conversion efficiency of 5.4%.
Interactions of Catalytic Enzymes with n-Type Polymers for High-Performance Metabolite Sensors
Publisher: American Chemical Society (ACS)
Date: 07-02-2023
Polaron spin dynamics in high-mobility polymeric semiconductors
Publisher: Springer Science and Business Media LLC
Date: 03-06-2019
The Chemistry and Applications of Heteroisoindigo Units as Enabling Links for Semiconducting Materials
Publisher: American Chemical Society (ACS)
Date: 17-11-2020
Challenges Facing the Nursing Profession in Saudi Arabia: An Integrative Review
Publisher: MDPI AG
Date: 31-05-2021
Abstract: There is a paucity of recent literature identifying the issues facing the nursing profession in Saudi Arabia. The aim of this integrative review is to highlight the ongoing challenges facing the nursing profession in Saudi Arabia despite attempts to make a difference and suggests recommendations for the future. Literature published from 2000 to 2020, inclusive, relevant for nursing challenges in Saudi Arabia was accessed and reviewed from multiple sources. In Saudi Arabia, inadequate numbers of Saudi nurses have prompted an increase in recruitment of expatriate nurses. This has created its own issues including, retention, lack of competency in English and Arabic, as well as Arabic cultural aspects, insufficient experience, and a high workload. The result is job dissatisfaction and increased attrition as these nurses prefer to move to more developed countries. For national nurses, the issues are the need to recruit more and retain these nurses. There are a range of cultural factors that contribute to these issues with national nurses. There is a need to improve the image of nursing to recruit more Saudi nurses as well as addressing issues in education and work environment. For expatriate nurses there is a need for a better recruitment processes, a thorough program of education to improve knowledge and skills to equip them to work and stay in Saudi. There is also a need for organizational changes to be made to increase the job satisfaction and retention of nurses generally. Healthcare in Saudi Arabia also needs leaders to efficiently manage the various issues associated with the nursing workforce challenges.
Design of experiment optimization of aligned polymer thermoelectrics doped by ion-exchange
Publisher: AIP Publishing
Date: 13-09-2021
DOI: 10.1063/5.0055886
Abstract: Organic thermoelectrics offer the potential to deliver flexible, low-cost devices that can directly convert heat to electricity. Previous studies have reported high conductivity and thermoelectric power factor in the conjugated polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT). Here, we investigate the thermoelectric properties of PBTTT films in which the polymer chains were aligned uniaxially by mechanical rubbing, and the films were doped by a recently developed ion exchange technique that provides a choice over the counterions incorporated into the film, allowing for more optimized morphology and better stability than conventional charge transfer doping. To optimize the polymer alignment process, we took advantage of two Design of Experiment (DOE) techniques: regular two-level factorial design and central composite design. Rubbing temperature Trub and post-alignment annealing temperature Tanneal were the two factors that were most strongly correlated with conductivity. We were able to achieve high polymer alignment with a dichroic ratio & and high electrical conductivities of up to 4345 S/cm for transport parallel to the polymer chains, demonstrating that the ion exchange method can achieve conductivities comparable/higher than conventional charge transfer doping. While the conductivity of aligned films increased by a factor of 4 compared to unaligned films, the Seebeck coefficient (S) remained nearly unchanged. The combination of DOE methodology, high-temperature rubbing, and ion exchange doping provides a systematic, controllable strategy to tune structure–thermoelectric property relationships in semiconducting polymers.
Acene Ring Size Optimization in Fused Lactam Polymers Enabling High n-Type Organic Thermoelectric Performance
Publisher: American Chemical Society (ACS)
Date: 22-12-2021
DOI: 10.1021/JACS.0C10365
Rapid single-molecule detection of COVID-19 and MERS antigens via nanobody-functionalized organic electrochemical transistors
Publisher: Springer Science and Business Media LLC
Date: 24-05-2021
Impact of Oligoether Side-Chain Length on the Thermoelectric Properties of a Polar Polythiophene
Publisher: American Chemical Society (ACS)
Date: 14-09-2023
Charge transport physics of a unique class of rigid-rod conjugated polymers with fused-ring conjugated units linked by double carbon-carbon bonds
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-04-2021
Abstract: The charge transport–limiting factors in conjugated polymers without single-bond linkages in the backbone have been identified.
Isostructural, Deeper Highest Occupied Molecular Orbital Analogues of Poly(3-hexylthiophene) for High-Open Circuit Voltage Organic Solar Cells
Publisher: American Chemical Society (ACS)
Date: 29-10-2013
DOI: 10.1021/CM4022563
Convection Driven Ultrarapid Protein Detection via Nanobody‐Functionalized Organic Electrochemical Transistors
Publisher: Wiley
Date: 28-07-2022
Abstract: Conventional biosensors rely on the diffusion‐dominated transport of the target analyte to the sensor surface. Consequently, they require an incubation step that may take several hours to allow for the capture of analyte molecules by sensor biorecognition sites. This incubation step is a primary cause of long s le‐to‐result times. Here, alternating current electrothermal flow (ACET) is integrated in an organic electrochemical transistor (OECT)‐based sensor to accelerate the device operation. ACET is applied to the gate electrode functionalized with nanobody–SpyCatcher fusion proteins. Using the SARS‐CoV‐2 spike protein in human saliva as an ex le target, it is shown that ACET enables protein recognition within only 2 min of s le exposure, supporting its use in clinical practice. The ACET integrated sensor exhibits better selectivity, higher sensitivity, and lower limit of detection than the equivalent sensor with diffusion‐dominated operation. The performance of ACET integrated sensors is compared with two types of organic semiconductors in the channel and grounds for device‐to‐device variations are investigated. The results provide guidelines for the channel material choice in OECT‐based biochemical sensors, and demonstrate that ACET integration substantially decreases the detection speed while increasing the sensitivity and selectivity of transistor‐based sensors.
Local Charge Trapping in Conjugated Polymers Resolved by Scanning Kelvin Probe Microscopy
Publisher: American Physical Society (APS)
Date: 17-12-2009
Thieno[3,2-b]thiophene-diketopyrrolopyrrole Containing Polymers for Inverted Solar Cells Devices with High Short Circuit Currents
Publisher: Wiley
Date: 17-06-2013
Ultrafast Energy Transfer Triggers Ionization Energy Offset Dependence of Quantum Efficiency in Low-bandgap Non-fullerene Acceptor Solar Cells
Publisher: Fundació Scito
Date: 25-01-2021
Author Correction: Intrinsic efficiency limits in low-bandgap non-fullerene acceptor organic solar cells.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2022
Membrane‐Free Detection of Metal Cations with an Organic Electrochemical Transistor
Publisher: Wiley
Date: 25-08-2019
Intercalated vs Nonintercalated Morphologies in Donor–Acceptor Bulk Heterojunction Solar Cells: PBTTT:Fullerene Charge Generation and Recombination Revisited
Publisher: American Chemical Society (ACS)
Date: 16-08-2017
DOI: 10.1021/ACS.JPCLETT.7B01571
Abstract: In this Letter, we study the role of the donor:acceptor interface nanostructure upon charge separation and recombination in organic photovoltaic devices and blend films, using mixtures of PBTTT and two different fullerene derivatives (PC
2D metal-organic frameworks for ultraflexible electrochemical transistors with high transconductance and fast response speeds
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-01-2023
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.
A study of the effects metal residues in poly(9,9-dioctylfluorene) have on field-effect transistor device characteristics
Publisher: Elsevier BV
Date: 10-2007
Dithiopheneindenofluorene (TIF ) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors
Publisher: Wiley
Date: 21-07-2017
Abstract: The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm
Intrinsic efficiency limits in low-bandgap non-fullerene acceptor organic solar cells
Publisher: Springer Science and Business Media LLC
Date: 23-10-2020
Aldol Polymerization to Construct Half-Fused Semiconducting Polymers
Publisher: American Chemical Society (ACS)
Date: 11-2021
Resolving Different Physical Origins toward Crystallite Imperfection in Semiconducting Polymers: Crystallite Size vs Paracrystallinity
Publisher: American Chemical Society (ACS)
Date: 10-11-2020
A nanobody-functionalized organic electrochemical transistor for the rapid detection of SARS-CoV-2 and MERS antigens at the physical limit
Publisher: Cold Spring Harbor Laboratory
Date: 13-11-2020
DOI: 10.1101/2020.11.12.20228874
Abstract: The COVID-19 pandemic highlights the need for rapid protein detection and quantification at the single-molecule level in a format that is simple and robust enough for widespread point-of-care applications. We here introduce a modular nanobody-organic electrochemical transistor architecture that enables the fast and specific detection and quantification of single-molecule to nanomolar protein antigen concentrations in complex bodily fluids. The sensor combines a new solution-processable organic semiconductor material in the transistor channel with the high-density and orientation-controlled bioconjugation of nanobody fusion proteins on disposable gate electrodes. It provides results after a 10 minutes exposure to 5 µL of unprocessed s les, maintains high specificity and single-molecule sensitivity in human saliva or serum, and is rapidly reprogrammed towards any protein target for which nanobodies exist. We demonstrate the use of this highly modular platform for the detection of green fluorescent protein, SARS-CoV-1/2, and MERS-CoV spike proteins and validate the sensor for COVID-19 screening in unprocessed clinical nasopharyngeal swab and saliva s les.
Effect of Fluorination on the Properties of a Donor–Acceptor Copolymer for Use in Photovoltaic Cells and Transistors
Publisher: American Chemical Society (ACS)
Date: 29-01-2013
DOI: 10.1021/CM301910T
Competition between the Charge Transfer State and the Singlet States of Donor or Acceptor Limiting the Efficiency in Polymer:Fullerene Solar Cells
Publisher: American Chemical Society (ACS)
Date: 16-12-2011
DOI: 10.1021/JA210029W
Abstract: We study the appearance and energy of the charge transfer (CT) state using measurements of electroluminescence (EL) and photoluminescence (PL) in blend films of high-performance polymers with fullerene acceptors. EL spectroscopy provides a direct probe of the energy of the interfacial states without the need to rely on the LUMO and HOMO energies as estimated in pristine materials. For each polymer, we use different fullerenes with varying LUMO levels as electron acceptors, in order to vary the energy of the CT state relative to the blend with [6,6]-phenyl C61-butyric acid methyl ester (PCBM). As the energy of the CT state emission approaches the absorption onset of the blend component with the smaller optical bandgap, E(opt,min) ≡ min{E(opt,donor) E(opt,acceptor)}, we observe a transition in the EL spectrum from CT emission to singlet emission from the component with the smaller bandgap. The appearance of component singlet emission coincides with reduced photocurrent and fill factor. We conclude that the open circuit voltage V(OC) is limited by the smaller bandgap of the two blend components. From the losses of the studied materials, we derive an empirical limit for the open circuit voltage: V(OC) ≲ E(opt,min)/e - (0.66 ± 0.08)eV.
Related Organisations
Imperial College London
Location: United Kingdom of Great Britain and Northern Ireland
King Abdullah University Of Science And Technology
Location: Saudi Arabia
King Abdullah University Of Science And Technology (KAUST)
Location: Saudi Arabia
University Of Oxford
Location: United Kingdom of Great Britain and Northern Ireland
University Of Strathclyde
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for Iain McCulloch.