scholarly journals Manipulating spatial alignment of donor and acceptor in host-guest MOF for TADF

2021 ◽  
Author(s):  
Xiao-Ting Liu ◽  
Weijie Hua ◽  
Hong-Xiang Nie ◽  
Mingxing Chen ◽  
Ze Chang ◽  
...  
Keyword(s):  
Excited States ◽  
Delayed Fluorescence ◽  
Energy Splitting ◽  
Time Resolved ◽  
Face To Face ◽  
Spatial Alignment ◽  
Stacking Pattern ◽  
Donor And Acceptor ◽  
Loading Ratio ◽  
Triplet Excited States

Abstract Thermally activated delayed fluorescence (TADF) was achieved when electron-rich triphenylene (Tpl) donors (D) were confined to a cage-based porous MOF host (NKU-111) composed of electron-deficient 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (Tpt) acceptor (A) as the ligand. The spatially-separated D and A molecules in a face-to-face stacking pattern generated strong through-space charge transfer (CT) interactions with a small singlet-triplet excited states energy splitting (∼0.1 eV), which enabled TADF. The resulting Tpl@NKU-111 exhibited an uncommon enhanced emission intensity as the temperature increased. Extensive steady-state and time-resolved spectroscopic measurements and first-principles simulations revealed the chemical and electronic structure of this compound in both the ground and low-lying excited states. A double-channel (T1, T2) intersystem crossing mechanism with S1 was found and explained as single-directional CT from the degenerate HOMO-1/HOMO of the guest donor to the LUMO + 1 of one of the nearest acceptors. The rigid skeleton of the compound and effective through-space CT enhanced the photoluminescence quantum yield (PLQY). A maximum PLQY of 57.36% was achieved by optimizing the Tpl loading ratio in the host framework. These results indicate the potential of the MOFs for the targeted construction and optimization of TADF materials.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

scholarly journals Exploiting trifluoromethyl substituents for tuning orbital character of singlet and triplet states to increase the rate of thermally activated delayed fluorescence

2020 ◽  
Vol 4 (12) ◽  
pp. 3602-3615 ◽  
Author(s):  
Jonathan S. Ward ◽  
Andrew Danos ◽  
Patrycja Stachelek ◽  
Mark A. Fox ◽  
Andrei S. Batsanov ◽  
...  
Keyword(s):  
Excited States ◽  
Organic Molecules ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Conjugated Organic Molecules ◽  
Singlet And Triplet States ◽  
Triplet Excited States ◽  
Orbital Character

This work shows that trifluoromethyl (CF3) substituents can be used to increase the rate of thermally activated delayed fluorescence (TADF) in conjugated organic molecules by tuning the excitonic character of the singlet and triplet excited states.

Study of an Oxadiazole Derivative for a Blue Thermally Activated Delayed Fluorescence Emitter

2015 ◽  
Vol 15 (10) ◽  
pp. 7828-7831 ◽  
Author(s):  
Dong Yuel Kwon ◽  
Geon Hyeong Lee ◽  
Young Sik Kim
Keyword(s):  
Excited States ◽  
Energy Gap ◽  
Delayed Fluorescence ◽  
Excited Singlet ◽  
Thermally Activated Delayed Fluorescence ◽  
Excited Triplet ◽  
Thermally Activated ◽  
Donor And Acceptor ◽  
Homo And Lumo ◽  
Dft And Tddft Calculations

Novel thermally activated delayed fluorescence (TADF) materials (ACR-OXD, 2ACR-OXD) with 9,10- dihydro-9,9-dimethylacridine (ACR) as an electron donor and oxadiazole derivative (OXD) as an electron acceptor were designed and theoretically investigated for blue OLED emitter. Using DFT and TDDFT calculations, we gained the electron distribution of HOMO and LUMO and the energy of the lowest singlet (S1) and the lowest triplet (T1) excited states. In comparison with the previously reported a xanthen derivative (ACR-XTN), ACR-OXD exhibits a promising blue TADF emitter because of destabilizing the LUMO of ACR-OXD by the change of the electron accepting group and maintaining the steric hindrance between donor and acceptor moieties which lead to efficient TADF due to the small energy gap between the lowest excited singlet (S1) state and the lowest excited triplet (T1) state.

Bond Shortening (1.4 Å) in the Singlet and Triplet Excited States of [Ir2(dimen)4]2+in Solution Determined by Time-Resolved X-ray Scattering

2011 ◽  
Vol 50 (19) ◽  
pp. 9329-9336 ◽  
Author(s):  
Kristoffer Haldrup ◽  
Tobias Harlang ◽  
Morten Christensen ◽  
Asmus Dohn ◽  
Tim Brandt van Driel ◽  
...  
Keyword(s):  
Excited States ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Triplet Excited States ◽  
Ray Scattering

Combined theoretical and time-resolved photoluminescence investigations of [Mo6Bri8Bra6]2− metal cluster units: evidence of dual emission

2015 ◽  
Vol 17 (43) ◽  
pp. 28574-28585 ◽  
Author(s):  
K. Costuas ◽  
A. Garreau ◽  
A. Bulou ◽  
B. Fontaine ◽  
J. Cuny ◽  
...  
Keyword(s):  
Excited States ◽  
Metal Cluster ◽  
Energy Shift ◽  
Dual Emission ◽  
Time Resolved ◽  
Nir Emission ◽  
Triplet Excited States ◽  
Time Resolved Photoluminescence

Distinct emissive species have been identified in [Mo6Bri8Bra6]2− containing systems. Strong geometrical relaxations of the triplet excited states are responsible for the huge energy shift leading to intense red-NIR emission.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

Optimization of a Safranine O three-component photoinitiating system for use in holographic recording

2015 ◽  
Vol 93 (12) ◽  
pp. 1345-1353 ◽  
Author(s):  
Ahmad Ibrahim ◽  
Bandar El Fouhaili ◽  
Aurélie Chan Yong ◽  
Christian Ley ◽  
Xavier Allonas ◽  
...  
Keyword(s):  
Excited States ◽  
Irradiation Time ◽  
Holographic Recording ◽  
Time Resolved ◽  
The Matrix ◽  
Resin Formulation ◽  
High Diffraction Efficiency ◽  
Triplet Excited States ◽  
Safranine O ◽  
High Diffraction

The coupling between a holographic resin, combining multiple monomers and additives, with photoinitiating systems (PIS) is not straightforward. In this paper, a classic PIS based on Safranine O (SFH+) as dye, an amine (ethyl-4-(dimethylamino)benzoate) as electron donor, and a triazine derivative (2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine) as electron acceptor for holographic recording was studied using time-resolved spectroscopic experiments. By taking into account the viscosity of the matrix, a method to evaluate the overall quantum yield of radicals released is proposed and the contribution of singlet and triplet excited states of SFH+ in the formation of radicals is evaluated. Then the corresponding photopolymerization efficiencies of the PIS, studied by real-time FTIR, are compared with holographic recording experiments: this system allows the formation of a hologram with high diffraction efficiency (0.9) in 3 s of irradiation time. It is shown that besides holographic resin formulation, the photochemistry of PIS also impacts the hologram formation.

Sign in / Sign up

Export Citation Format

Share Document