A5043244519- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Luminescence and Fluorescent Materials
- Organic Light-Emitting Diodes Research
- Organic Electronics and Photovoltaics
- Photochemistry and Electron Transfer Studies
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Molecular Sensors and Ion Detection
- Analytical Chemistry and Sensors
- Synthesis and Properties of Aromatic Compounds
- Chemistry and Chemical Engineering
- Conducting polymers and applications
- Click Chemistry and Applications
- Radical Photochemical Reactions
- Photoreceptor and optogenetics research
- Synthesis and Biological Evaluation
- Quantum optics and atomic interactions
- Advanced Memory and Neural Computing
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Supramolecular Chemistry and Complexes
- Quantum and electron transport phenomena
- Fullerene Chemistry and Applications
- Various Chemistry Research Topics
Northumbria University
2020-2024
Durham University
2012-2023
University of Bristol
2022
Durham Technical Community College
2017-2020
Newcastle upon Tyne Hospital
2020
University of Cambridge
2014
Abstract Knowing the underlying photophysics of thermally activated delayed fluorescence (TADF) allows proper design high efficiency organic light-emitting diodes. We have proposed a model to describe reverse intersystem crossing (rISC) in donor–acceptor charge transfer molecules, where spin–orbit coupling between singlet and triplet states is mediated by one local donor (or acceptor). This second order, vibronically coupled mechanism describes basic TADF. Through series measurements,...
Abstract A new family of anthracene core, highly fluorescent emitters is synthesized which include diphenylamine hole transport end groups. Using a very simple one or two layer organic light emitting diode (OLED) structure, devices without outcoupling achieve an external quantum efficiency 6% and photonic efficiencies 20 cd/A. The theoretical maximum such should not exceed 3.55%. Detailed photophysical characterization shows that for these based 2T 1 ≤T n so in this special case, triplet...
Abstract Regio- and conformational isomerization are fundamental in chemistry, with profound effects upon physical properties, however their role excited state properties is less developed. Here two regioisomers of bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene- S,S -dioxide, a donor–acceptor–donor (D–A–D) thermally-activated delayed fluorescence (TADF) emitter, studied. 2,8-bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene- -dioxide exhibits only one quasi-equatorial conformer on both...
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...
Small, apolar aromatic groups, such as phenyl rings, are commonly included in the structures of fluorophores to impart hindered intramolecular rotations, leading desirable solid-state luminescence properties. However, they not normally considered take part through-space interactions that influence fluorescent output. Here, we report on photoluminescence properties a series phenyl-ring molecular rotors bearing three, five, six, and seven groups. The emissions from two found originate,...
This review summarises the significant developments in our understanding and control of thermally-activated delayed fluorescence (TADF) molecules spin–vibronic coupling mechanism, from which we have designed new generations emitters.
Dual luminescence (RTP and TADF) is observed in a series of donor–acceptor–donor molecules.
We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from presence persistent dimer states thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation this state 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals influence species on purity its photoluminescence electroluminescence. The is sensitive to sample preparation method, enduring contributes widely reported...
Understanding the excited-state dynamics and conformational relaxation in thermally activated delayed fluorescence (TADF) molecules, including conformations that potentially support intramolecular through-space charge transfer, can open new avenues for TADF molecular design as well elucidate complex photophysical pathways structurally molecules. Emissive molecules comprising a donor (triphenylamine, TPA) an acceptor (triphenyltriazine, TRZ) bridged by second...
A new TADF emitter is presented showing near-infrared efficient emission.
Rather than donor–acceptor dihedral angles, the TADF performance of DMAC–BZN positional isomers is instead controlled by differences in acceptor strength arising from π-system electron density – along with a through-space dipole interaction.
Twisted carbazoles and shallow dihedral angles provide a defence against dimer formation that adversely affects OLED performance.
Herein, we expose how the antagonistic relationship between solid-state luminescence and photocyclization of oligoaryl alkene chromophores is modulated by conjugation length their alkenyl backbones. Heptaaryl cycloheptatriene molecular rotors exhibit aggregation-induced emission characteristics. We show that turned off upon breaking epoxide formation. While this modification deleterious to photoluminescence, it enables formation extended polycyclic frameworks Mallory reactions. exploit...
A new iptycene unequivocally validates homoconjugation as a viable strategy to simultaneously enhance TADF reverse intersystem crossing and radiative decay.
We report magnetoconductance measurements on polymer:fullerene photovoltaic devices in the regime of high fields and low temperatures, where spin polarization injected carriers plays an important role. The current either decreases or increases with magnetic field, depending whether interfacial charge-transfer state lies above below intramolecular triplet energy. Rapid transitions from states to lower-lying excitons constitute loss mechanism that is responsible for negative observed.
Thermally activated delayed fluorescence has been found in a group of tricarbazolylamines that are purely electron-donating, non-charge-transfer (CT) molecules. We show the reverse intersystem crossing step these materials is mediated through upper triplet states. Reverse internal conversion shown to be thermally mechanism behind harvesting mechanism. The strongly mixed n−π*/π–π* character lowest energy optical transitions retains high oscillator strength and gives rise ΦPL. Organic...
Emitters showing thermally activated delayed fluorescence (TADF) in electroluminescent devices rely on efficient reverse intersystem crossing (rISC) arising from small thermal activation barriers between the lowest excited triplet and singlet manifolds. A donor–acceptor compound consisting of a demethylacridine donor methylbenzoate acceptor group is used as model TADF emitter. The spectroscopic signatures this system are characterized using combination photoluminescence excitation, decay...
Heterocyclic dimers consisting of combinations butterfly-shaped phenothiazine (PTZ) and its chemically oxidized form phenothiazine-5,5-dioxide (PTZ(SO
A versatile <italic>N</italic>-alkylation strategy controls the presence of charge-transfer excited states and emission colour N-heterocyclic chromophores.
Greater than the sum of its parts – a 3D ICT molecule displays greatly improved optoelectronic properties over 2D analogue.
Switching on thermally activated delayed fluorescence through quaternisation of an sp 2 -hybridised nitrogen atom.
In tweezer-like dinuclear platinum( ii ) complexes, the exchange of chloride ligand for thiocyanate promotes interfacial interactions, leading to low-energy emission.
Anisotropy within three TADF materials has been observed using steady-state fluorescence polarization. This technique allowed for the observation of differences in polarization dilute solution, and both unstretched stretched films; latter producing highly aligned molecules sample. Using these films anisotropy can be between emission from 1LE 1CT states upon exciting different absorption bands. Furthermore, time-resolved measurements highlights strong vibronic coupling charge-transfer local...
4DTPIPN has a strong tendency for dimer formation, even in dilute film, and possesses higher colour purity than 4CzIPN but this is traded-off against the photoluminescence quantum yield. (Credit to LeStudio/Shutterstock James Bond themed background.)