A5021705748- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Luminescence and Fluorescent Materials
- Molecular Junctions and Nanostructures
- Conducting polymers and applications
- Photochemistry and Electron Transfer Studies
- Perovskite Materials and Applications
- Synthesis and Properties of Aromatic Compounds
- Organic and Molecular Conductors Research
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Liquid Crystal Research Advancements
- Crystallography and molecular interactions
- Advanced Sensor and Energy Harvesting Materials
- Lanthanide and Transition Metal Complexes
- Organoboron and organosilicon chemistry
- Electron Spin Resonance Studies
- Photochromic and Fluorescence Chemistry
- Advanced Memory and Neural Computing
- Porphyrin and Phthalocyanine Chemistry
- Photoreceptor and optogenetics research
- Quantum and electron transport phenomena
- Quantum Dots Synthesis And Properties
University of Namur
2019-2025
University of Mons
2015-2024
Namur Institute of Structured Matter
2019-2024
University of Leeds
2023
Center for Innovation
2017
Novel (United States)
2015-2017
University of Cambridge
2013-2015
Material (Belgium)
2012-2015
Materia Nova
2011
Université Libre de Bruxelles
2009
Abstract Since the first report in 2015, multiresonant thermally activated delayed fluorescent (MR‐TADF) compounds, a subclass of TADF emitters based on heteroatom‐doped nanographene material, have come to fore as attractive hosts well for organic light‐emitting diodes (OLEDs). MR‐TADF compounds typically show very narrow‐band emission, high photoluminescence quantum yields, and small Δ E ST values, around 200 meV, coupled with chemical thermal stabilities. These materials properties...
Abstract Unlike conventional thermally activated delayed fluorescence chromophores, boron-centered azatriangulene-like molecules combine a small excited-state singlet-triplet energy gap with high oscillator strengths and minor reorganization energies. Here, using highly correlated quantum-chemical calculations, we report this is driven by short-range of the electron density taking place upon electronic excitation these multi-resonant structures. Based on finding, design series π-extended...
Quantum-chemical calculations are combined to a model Frenkel-Holstein Hamiltonian assess the nature of lowest electronic excitations in pentacene crystal. We show that an admixture charge-transfer into singlet excited states form origin Davydov splitting and mediate instantaneous exciton fission by direct optical excitation coherently coupled single double states, agreement with recent experiments.
A theory for polarized absorption in crystalline oligoacenes is presented, which includes Frenkel exciton coupling, the coupling between and charge-transfer (CT) excitons, of all neutral ionic excited states to dominant ring-breathing vibrational mode. For tetracene, spectra calculated using couplings among five lowest energy molecular singlet predict a Davydov splitting (DS) (0-0) vibronic band only -32 cm(-1), far smaller than measured value 631 cm(-1) wrong sign-a negative sign indicating...
Polyphenols (synthetically modified or directly provided by human diet) scavenge free radicals H-atom transfer and may thus decrease noxious effects due to oxidative stress. Free radical scavenging polyphenols has been widely theoretically studied from the thermodynamic point of view whereas kinetic much less addressed. The present study describes kinetic-based structure–activity relationship for quercetin. This compound is very characteristic wide flavonoid subclass polyphenols. a mechanism...
Abstract A new design strategy is introduced to address a persistent weakness with resonance thermally activated delayed fluorescence (R‐TADF) emitters reduce aggregation‐caused quenching effects, which are identified as one of the key limiting factors. The emitter Mes 3 DiKTa shows an improved photoluminescence quantum yield 80% compared 75% for reference in 3.5 wt% 1,3‐bis( N ‐carbazolyl)benzene. Importantly, emission from aggregates, even at high doping concentrations, eliminated and...
An easy-to-access, near-UV-emitting linearly extended B,N-doped heptacene with high thermal stability is designed and synthesized in good yields. This compound exhibits thermally activated delayed fluorescence (TADF) at ambient temperature from a multiresonant (MR) state represents rare example of non-triangulene-based MR-TADF emitter. At lower temperatures triplet-triplet annihilation dominates. The simultaneously possesses narrow, deep-blue emission CIE coordinates (0.17, 0.01). While...
The structural organization of three different families semicrystalline π‐conjugated polymers is reported (poly(3‐hexylthiophene) (P3HT), poly[2,6‐(4,4‐bis‐alkyl‐4H‐cyclopenta‐[2,1‐b;3,4‐b0]‐dithiophene)‐ alt ‐4,7‐(2,1,3‐benzothiadiazole)](cyclopentadithiophene‐benzothiadiazole) (CDT‐BTZ) and poly(N,N"‐bis‐2‐octyldodecylnaphtalene‐1,4,5,8‐bis‐dicarboximide‐2,6‐diyl‐ ‐5,5–2,2‐bithiophene (P(NDI2OD‐T2))). These have triggered significant interest for their remarkable charge‐transport...
Abstract Herein, we reported an ultrapure blue multiple‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) material ( ν‐DABNA‐O‐Me ) with a high photoluminescence quantum yield and large rate constant for reverse intersystem crossing. Because of restricted π‐conjugation the HOMO rather than LUMO induced by oxygen atom incorporation, shows hypsochromic shift compared to parent MR‐TADF ν‐DABNA ). An organic light‐emitting diode based on this exhibits emission at 465 nm, small...
With the surge of interest in multiresonant thermally activated delayed fluorescent (MR-TADF) materials, it is important that there exist computational methods to accurately model their excited states. Here, building on our previous work, we demonstrate how spin-component scaling second-order approximate coupled-cluster (SCS-CC2), a wavefunction-based method, robust at predicting ΔEST (i.e., energy difference between lowest singlet S1 and triplet T1 states) large number MR-TADF with mean...
Abstract Molecules present a versatile platform for quantum information science 1,2 and are candidates sensing computation applications 3,4 . Robust spin-optical interfaces key to harnessing the resources of materials 5 To date, carbon-based have been non-luminescent 6,7 , which prevents optical readout via emission. Here we report organic molecules showing both efficient luminescence near-unity generation yield excited states with spin multiplicity S > 1. This was achieved by designing...
In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require presence of acceptor atoms. Based on an in silico design, compound DiICzMes4 possesses red-shifted emission, enhanced photoluminescence quantum yield, and smaller singlet-triplet energy gap, ΔEST, than parent indolocarbazole induces MR-TADF properties. Coupled cluster calculations accurately predict magnitude ΔEST when optimized...
Strategies to tune the emission of multiresonant thermally activated delayed fluorescence (MR-TADF) emitters remain rare. Here, we explore effect donor substitution about a MR-TADF core on energy and nature excited state. We decorate different numbers types electron-donors central core, DiKTa. Depending identity number groups, state either remains short-range charge transfer (SRCT) thus characteristic an emitter or becomes long-range (LRCT) that is typically observed in donor-acceptor TADF...
The poor operational stability of non-fullerene electron acceptor (NFA) organic solar cells (OSCs) currently limits their commercial application. While previous studies have primarily focused on the degradation NFA component, we also consider here donor material. We examine three representative polymers, PM6, D18, and PTQ10, paired with benchmark NFA, Y6. After light soaking PM6 D18 in air, find an enhanced conversion singlet excitons into trapped interchain polaron pairs sub-100 femtosecond...
Two multiresonant thermally activated delayed fluorescence (MR-TADF) emitters are presented and it is shown how further borylation of a deep-blue MR-TADF emitter, DIDOBNA-N, both blueshifts narrows the emission producing new near-UV MesB-DIDOBNA-N, shown. DIDOBNA-N emits bright blue light (ΦPL = 444 nm, FWHM 64 ΦPL 81%, τd 23 ms, 1.5 wt% in TSPO1). The organic light-emitting diode (OLED) based on this twisted compound shows very high maximum external quantum efficiency (EQEmax ) 15.3% for...
A design strategy for efficient MR-TADF emitters needs (i) avoiding aggregation by inducing steric hindrance at peripheral strategic positions, and (ii) combining lateral groups of higher donor character as compared to the central core.
A series of bulky end-capped [1]benzothieno[3,2-b]benzothiophenes (BTBTs) are developed in order to tune the packing structure via terminal substitution. coupled theoretical and experimental study allows us identify 2,7-di-tert-butylBTBT as a new high-performance organic semiconductor with large well-balanced transfer integrals, evidenced by quantum-chemical calculations. Single-crystal field-effect transistors show remarkable average saturation mobility 7.1 cm2 V−1 s−1.
We present a Monte Carlo approach to estimate how molecular parameters impact hopping rates and charge mobilities in organic pi-conjugated materials. Our goal is help establishing structure-properties relationships. As first step, our illustrated by considering model system made of one-dimensional array pentacene molecules; we describe the variations electron-transfer resulting as function electric field presence disorder traps. The results highlight that there no direct relationship between...
A novel nonadiabatic molecular dynamics scheme is applied to study the singlet fission (SF) process in pentacene dimers as a function of longitudinal and lateral displacements backbones. Detailed two-dimensional mappings both instantaneous long-term triplet yields are obtained, characterizing advantageous unfavorable stacking arrangements, which can be achieved by chemical substitutions bare molecule. We show that SF rate increased more than an order magnitude through tuning intermolecular...
Thermally activated delayed fluorescence (TADF) offers promise for all-organic light-emitting diodes with quantum efficiencies competing those of transition-metal-based phosphorescent devices. While computational efforts have so far largely focused on gas-phase calculations singlet and triplet excitation energies, the design TADF materials requires multiple methodological developments targeting among others a quantitative description electronic energetics, fully accounting environmental...
Singlet excitons in $\ensuremath{\pi}$-stacked molecular crystals can split into two triplet a process called singlet fission that opens route to carrier multiplication photovoltaics. To resolve controversies about the mechanism of fission, we have developed first principles nonadiabatic quantum dynamical model reveals critical role stacking symmetry and provides unified picture coherent versus thermally activated mechanisms different acenes. The slip-stacked equilibrium packing structure...