Synthesis and Photophysical Properties of Purine-Phenoxazine and Purine-Phenothiazine Conjugates

2021 ◽  
Vol 903 ◽  
pp. 155-161
Author(s):  
Armands Sebris ◽  
Kaspars Traskovskis ◽  
Irina Novosjolova ◽  
Māris Turks
Keyword(s):  
Thin Layer ◽  
Benzene Ring ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Thermally Activated Delayed Fluorescence ◽  
Layer Film ◽  
Thermally Activated

Electron donating phenoxazine and phenothiazine groups were introduced in an electron deficient purine structure through a benzene ring bridge to facilitate thermally activated delayed fluorescence. Mitsunobu and Suzuki-Miyaura reactions were used to synthesize the target compounds. Photophysical properties of target compounds were explored and quantum yields in the thin layer film reached up to 8 % and in the PMMA doped thin layer film up to 15 %.

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 Solution-Processed OLEDs Based on Thermally Activated Delayed Fluorescence Copper(I) Complexes with Intraligand Charge-Transfer Excited State

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1125
Author(s):  
Teng Teng ◽  
Jinfan Xiong ◽  
Gang Cheng ◽  
Changjiang Zhou ◽  
Xialei Lv ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Functional Theory ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Wide Range

A new series of tetrahedral heteroleptic copper(I) complexes exhibiting efficient thermally-activated delayed fluorescence (TADF) in green to orange electromagnetic spectral regions has been developed by using D-A type N^N ligand and P^P ligands. Their structures, electrochemical, photophysical, and electroluminescence properties have been characterized. The complexes exhibit high photoluminescence quantum yields (PLQYs) of up to 0.71 at room temperature in doped film and the lifetimes are in a wide range of 4.3–24.1 μs. Density functional theory (DFT) calculations on the complexes reveal the lowest-lying intraligand charge-transfer excited states that are localized on the N^N ligands. Solution-processed organic light emitting diodes (OLEDs) based on one of the new emitters show a maximum external quantum efficiency (EQE) of 7.96%.

Outstanding blue delayed fluorescence and significant processing stability of cuprous complexes with functional pyridine–pyrazolate diimine ligands

2015 ◽  
Vol 44 (15) ◽  
pp. 6706-6710 ◽  
Author(s):  
Qing Zhang ◽  
Jun Chen ◽  
Xiao-Yuan Wu ◽  
Xu-Lin Chen ◽  
Rongmin Yu ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Diimine Ligands ◽  
Processing Stability

Five cuprous complexes display outstanding blue thermally activated delayed fluorescence (TADF) with quantum yields near 1 and significant processing stability from the solid to the solvent states.

scholarly journals Regioisomeric Effect on the Excited-State Fate Leading to Room-Temperature Phosphorescence or Thermally Activated Delayed Fluorescence in a Dibenzophenazine-Cored Donor–Acceptor–Donor System

2021 ◽  
Author(s):  
Takumi Hosono ◽  
Nicolas Oliveira Decarli ◽  
Paola Zimmermann Crocomo ◽  
Tsuyoshi Goya ◽  
Leonardo Evaristo de Sousa ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Room Temperature Phosphorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
Emission Behavior

Exploring design principle for switching thermally activated dealyed fluorescecne (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies on the regioisomeric and substituents effects in a twisted donor–acceptor–donor (D–A–D) scaffold (A = dibenzo[a,j]phenazine; D = dihydrophenazasiline) on the fate of the excited state have been performed. The study revealed that the regiosiomerism clearly affects the emission behavior of the D–A–D compounds. Distinct difference in TADF, dual TADF & RTP, and dual RTP were observed, depending on the host used. Furthermore, OLED organic light-emitting diodes (OLEDs) fabricated with the developed emitters achieved high external quantum yields for RTP-based OLEDS up to 7.4%.

scholarly journals A Singlet Oxygen Photogeneration and Luminescence Study of Unsymmetrically Substituted Mesoporphyrinic Compounds

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Anabela Sousa Oliveira ◽  
Dumitru Licsandru ◽  
Rica Boscencu ◽  
Radu Socoteanu ◽  
Veronica Nacea ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Mean Values ◽  
Oxygen Generation ◽  
Fluorescence Quantum Yields ◽  
Thermally Activated ◽  
Phosphorescence Emission ◽  
Photophysical Studies

This paper deals with a series of new unsymmetrically substituted mesoporphyrins: 5-(2-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHO), 5-(3-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHM), 5-(4-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHP), 5-(2-hydroxyphenyl)-10,15,20-tris-butyl-21,23-H-porphyrin (TBPOHO), and their parent nonsubstituted compounds, respectively, 5,10,15,20-tetrakis-phenyl-21,23-H-porphyrin (TPP) and 5,10,15,20-tetrakis-butyl-21,23-H-porphyrin (TBP). Several photophysical studies were carried out to access the influence of the unsymmetrical substitution at the porphyrinic macrocycle on porthyrin's photophysical properties, especially porthyrin's efficiency as singlet oxygen sensitizers. The quantum yields of singlet oxygen generation were determined in benzene (ΦΔ(TPP) = 0.66 ± 0.05;ΦΔ(TPPOHO) = 0.69 ± 0.04;ΦΔ(TPPOHM) = 0.62 ± 0.04;ΦΔ(TPPOHP) = 0.73 ± 0.03;ΦΔ(TBP) = 0.76 ± 0.03;ΦΔ(TBPOHO) = 0.73 ± 0.02) using the 5,10,15,20-tetraphenyl-21,23-H-porphine (ΦΔ(TPP) = 0.66) and Phenazine (ΦΔ(Phz) = 0.83) as reference compounds. Their fluorescence quantum yields were found to be (Φf(TPPOHO) = 0.10 ± 0.04;Φf(TPPOHM) = 0.09 ± 0.03;Φf(TPPOHP) = 0.13 ± 0.02;Φf(TBP) = 0.08 ± 0.03 andΦf(TBPOHO) = 0.08 ± 0.02 using 5,10,15,20-tetraphenyl-21,23-H-porphine as referenceΦf(TPP) = 0.13). Singlet state lifetimes were also determined in the same solvent. All the porphyrins presented very similar fluorescence lifetimes (mean values ofτS(withO2, air equilibrated) = 9.6 ± 0.3 nanoseconds and (withoutO2, argon purged) = 10.1 ± 0.6 nanoseconds, resp.). The phosphorescence emission was found to be negligible for this series of unsymmetrically substituted mesoporphyrins, but an E-type, thermally activated, delayed fluorescence process was proved to occur at room temperature.

scholarly journals Using the Mechanical Bond to Tune the Performance of a Thermally Activated Delayed Fluorescence Emitter

2021 ◽  
Author(s):  
P Rajamalli ◽  
Federica Rizzi ◽  
Wenbo Li ◽  
Michael Jinks ◽  
Abhishek Gupta ◽  
...  
Keyword(s):  
Weak Interactions ◽  
Photophysical Properties ◽  
Energy Difference ◽  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
X Ray Crystallography ◽  
Thermally Activated ◽  
Mechanical Bond

We report the characterization of rotaxanes based on a carbazole–benzophenone thermally activated delayed fluorescence luminophore. We find that the mechanical bond leads to an improvement in key photophysical properties of the emitter, notably an increase in photoluminescence quantum yield and a decrease in the energy difference between singlet and triplet states, as well as fine tuning of the emission wavelength, a feat that is difficult to achieve when using covalently bound substituents. Computational simulations, supported by X-ray crystallography, suggest that this tuning of properties occurs due to weak interactions between the axle and the macrocycle that are enforced by the mechanical bond. This work highlights the benefits of using the mechanical bond to refine existing luminophores, providing a new avenue for emitter optimization that can ultimately increase the performance of these molecules.

A red thermally activated delayed fluorescence emitter employing dipyridophenazine with a gradient multi-inductive effect to improve radiation efficiency

2019 ◽  
Vol 7 (25) ◽  
pp. 7525-7530 ◽  
Author(s):  
Huiqin Wang ◽  
Bingjie Zhao ◽  
Peng Ma ◽  
Zhe Li ◽  
Xinyu Wang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Inductive Effect ◽  
Intramolecular Charge Transfer ◽  
Radiative Transition ◽  
Delayed Fluorescence ◽  
Radiation Efficiency ◽  
Quantum Yields ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Electro Luminescence

Red TADF emitter oTPA-DPPZ employs dipyridophenazine with gradient multi-inductive effect as acceptor, which enhances intramolecular charge transfer and radiative transition, resulting photo- and electro-luminescence quantum yields of 75% and 18.5%.

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