A5061347276- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Perovskite Materials and Applications
- Organic Light-Emitting Diodes Research
- Luminescence and Fluorescent Materials
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Molecular Junctions and Nanostructures
- Synthesis and Properties of Aromatic Compounds
- Fullerene Chemistry and Applications
- Photochemistry and Electron Transfer Studies
- Quantum Dots Synthesis And Properties
- solar cell performance optimization
- Thin-Film Transistor Technologies
- Lanthanide and Transition Metal Complexes
- Advanced Chemical Physics Studies
- Porphyrin and Phthalocyanine Chemistry
- Strong Light-Matter Interactions
- Spectroscopy and Quantum Chemical Studies
- Thermal Radiation and Cooling Technologies
- Nonlinear Optical Materials Research
- Chalcogenide Semiconductor Thin Films
- Synthetic Organic Chemistry Methods
- Nanoplatforms for cancer theranostics
- Photovoltaic Systems and Sustainability
University of Cambridge
2008-2025
Cavendish Hospital
2021-2022
The Faraday Institution
2021
University College London
2013-2018
Texas A&M University at Qatar
2016
Imperial College London
2008-2016
Transnational Press London
2014-2016
University of Washington
2009-2012
University of Gothenburg
2008-2009
King's College London
2007
The tolerance factor is a widely used predictor of perovskite stability. recent interest in hybrid perovskites for use as solar cell absorbers has lead to application the these materials way explain and predict structure. Here we critically assess suitability halide perovskites. We show that fails accurately stability 32 known inorganic iodide perovskites, propose an alternative method. introduce revised set ionic radii cations anion dependent, this revision necessary due increased covalency...
We report the synthesis and polymerization of a novel thieno[3,2-b]thiophene−diketopyrrolopyrrole-based monomer. Copolymerization with thiophene afforded polymer maximum hole mobility 1.95 cm2 V−1 s−1, which is highest from polymer-based OFET reported to date. Bulk-heterojunction solar cells comprising this PC71BM gave power conversion efficiency 5.4%.
Systematically moving the alkyl-chain branching position away from polymer backbone afforded two new thieno[3,2-b]thiophene-diketopyrrolopyrrole (DPPTT-T) polymers. When used as donor materials in polymer:fullerene solar cells, efficiencies exceeding 7% were achieved without use of processing additives. The effect point on thin-film morphology was investigated using X-ray scattering techniques and effects photovoltaic charge-transport properties also studied. For both cell transistor...
The prospect of using low cost, high throughput material deposition processes to fabricate organic circuitry and solar cells continues drive research towards improving the performance semiconducting materials utilized in these devices. Conjugated aromatic polymers have emerged as a leading candidate semiconductor class, due their combination amenability processing reasonable electrical optical performance. Challenges remain, however, further improve charge carrier mobility for transistor...
Two novel indacenodithiophene (IDT) based donor–acceptor conjugated polymers for use in organic field effect transistors and photovoltaic devices are synthesized characterized. The of inclusion two fluorine atoms on the acceptor portion polymer is thoroughly investigated via a range techniques. inductively withdrawing mesomerically donating properties result decrease highest occupied molecular orbital (HOMO), with little lowest unoccupied (LUMO) as demonstrated through density functional...
Harnessing the near-infrared (NIR) region of electromagnetic spectrum is exceedingly important for photovoltaics, telecommunications, and biomedical sciences. While thermally activated delayed fluorescent (TADF) materials have attracted much interest due to their intense luminescence narrow exchange energies (ΔEST), they are still greatly inferior conventional dyes in NIR, which precludes application. This because securing a sufficiently strong donor-acceptor (D-A) interaction NIR emission...
Abstract Hyperfluorescence shows great promise for the next generation of commercially feasible blue organic light-emitting diodes, which eliminating Dexter transfer to terminal emitter triplet states is key efficiency and stability. Current devices rely on high-gap matrices prevent transfer, unfortunately leads overly complex from a fabrication standpoint. Here we introduce molecular design where ultranarrowband emitters are covalently encapsulated by insulating alkylene straps. Organic...
Abstract The coupling of excitons in π-conjugated molecules to high-frequency vibrational modes, particularly carbon–carbon stretch modes (1,000–1,600 cm −1 ) has been thought be unavoidable 1,2 . These accelerate non-radiative losses and limit the performance light-emitting diodes, fluorescent biomarkers photovoltaic devices. Here, by combining broadband impulsive spectroscopy, first-principles modelling synthetic chemistry, we explore exciton–vibration a range molecules. We uncover two...
The ability of chemists to design and synthesize pi-conjugated organic polymers with precise control remains the key technological breakthroughs for using polymer materials in electronic photonic devices. In this communication, controlled chain-growth polymerization regioregular poly(3-hexylthiophene) (P3HT) from an external initiator 1,3-bis(diphenylphosphino)propane (dppp) as a catalyst ligand is reported. complexes cis-chloro(phenyl)(dppp)nickel(II) cis-chloro(o-tolyl)(dppp)nickel(II)...
A detailed charge recombination mechanism is presented for organic photovoltaic devices with a high open-circuit voltage. In binary blend comprised of polyfluorene copolymers, the performance-limiting process found to be efficient tightly bound pairs into neutral triplet excitons. We arrive at this conclusion using optical transient absorption (TA) spectroscopy visible and IR probes over seven decades time resolution. By resolving polarization TA signal, we track movement polaronic states...
The energetic driving force required to drive charge separation across donor/acceptor heterojunctions is a key consideration for organic optoelectronic devices. Herein we report series of transient absorption and photocurrent experiments as function excitation wavelength temperature two low-band-gap polymer/fullerene blends study the mechanism at interface. For blend that exhibits smallest LUMO energy level offset, quantum yield falls photon reduced toward band gap, but bound, interfacial...
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTIndacenodithiophene-co-benzothiadiazole Copolymers for High Performance Solar Cells or Transistors via Alkyl Chain OptimizationHugo Bronstein†, Dong Seok Leem†, Richard Hamilton‡, Paul Woebkenberg†, Simon King†, Weimin Zhang†, Raja Shahid Ashraf†, Martin Heeney†, Thomas D. Anthopoulos†, John de Mello†, and Iain McCulloch*†View Author Information† Department of Chemistry, Centre Plastic Electronics, Imperial...
The photostability of two donor polymers, DPP-TT-T and PTB7, is compared in neat films blend with PC71BM. In both films, PTB7 shown to be relatively unstable. This observation correlate transient optical studies long lived polymer triplets molecular probe singlet oxygen yields.
A series of low bandgap indacenodithiophene polymers is purified by recycling SEC in order to isolate narrow polydispersity fractions. This additional purification step found have a significant beneficial influence on the solar cell performance and reasons for this increase are investigated.
Singlet fission, the process of forming two triplet excitons from one singlet exciton, is a characteristic reserved for only handful organic molecules due to atypical energetic requirement low energy excited states. The predominant strategy achieving such trait by increasing ground state diradical character; however, this greatly reduces ambient stability. Herein, we exploit Baird's rule aromaticity manipulate singlet-triplet gap and create novel fission candidates. We achieve through...
We report a general light processing strategy for organic solar cells (OSC) that exploits the propensity of fullerene derivative PC60BM to photo-oligomerize, which is capable both stabilizing polymer:PC60BM active layer morphology and enhancing device stability under thermal annealing. The observations hold blends with an array benchmark donor polymer systems, including P3HT, DPP-TT-T, PTB7, PCDTBT. kinetics thermally induced crystallization within blend films are investigated as function...
The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the exciton diffusion lengths and has direct impact on photocurrent generation by devices. However, very little known about material properties controlling lifetimes excitons, with most our knowledge originating from studies small molecules. Herein, we provide brief summary nature excited states then present an analysis 16 semiconducting...
Exciton-polaritons are quasiparticles with mixed photon and exciton character that demonstrate rich quantum phenomena, novel optoelectronic devices the potential to modify chemical properties of materials. Organic materials current interest as active for their ability sustain exciton-polaritons even at room temperature. However, within organic devices, it is often 'dark' spin-1 triplet excitons dominate operation. These triplets have been largely ignored in treatments polaritons, which...
The presence of energetically low-lying triplet states is a hallmark organic semiconductors. Even though they present wealth interesting photophysical properties, these optically dark significantly limit optoelectronic device performance. Recent advances in emissive charge-transfer molecules have pioneered routes to reduce the energy gap between triplets and "bright" singlets, allowing thermal population exchange them eliminating significant loss channel devices. In conjugated polymers, this...
The synthesis of a new thieno[3,2‐ b ]thiophene isoindigo (iITT) based monomer unit, and its subsequent incorporation into series alternating copolymers is reported. Copolymerisation with benzothiadiazole, bithiophene thiophene comonomer units by palladium catalysed cross coupling gives three narrow band gap semiconducting polymers for OFET applications. Extending the fused nature core serves to further enhance molecular orbital overlap along polymer backbones facilitate good charge...
Two-dimensional covalent-organic frameworks (2D-COFs) on surfaces offer a facile route to new 2D materials. Schiff-base condensation reactions have proven be an effective fabrication for such We present scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) studies of porphyrin 2D-COFs grown at solid-vapour interface. XPS shows that covalent links between porphyrins consist mixture imines hemiaminals, non-conjugated intermediate in the reaction. These results...