Novel D–A chromophores with condensed 1,2,4-triazine system simultaneously display thermally activated delayed fluorescence and crystallization-induced phosphorescence

Maggiore, Antonio; Tan, Xiaofeng; Brosseau, Arnaud; Danos, Andrew; Miomandre, Fabien; Monkman, Andrew P.; Audebert, Pierre; Clavier, Gilles

doi:10.1039/d2cp00777k

Cited by 15 publications

(11 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[9] Even more critical for the appearance of phosphorescence is the suppression of fast non-radiative relaxation from the excited triplet state to the ground state, caused by for example collisions with solvent molecules and/or oxygen triplet quenching. [10] This can be realized by controlling the molecular packing, i. e. doping the emitter in a rigid host material, [11] crystallization, [12] or the introduction of organic frameworks. [13] Without the benefits of a rigid environment, it becomes especially challenging to develop materials that exhibit RTP in solution (sRTP), as the increased molecular motions and vibrational degrees of freedom greatly enhance non-radiative decay in competition with triplet emission.…”

Section: Introductionmentioning

confidence: 99%

Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence

Paredis

Cardeynaels

Kuila

et al. 2023

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Metal-free organic emitters that display solutionphase room temperature phosphorescence (sRTP) remain exceedingly rare. Here, we investigate the structural and photophysical properties that support sRTP by comparing a recently reported sRTP compound (BTazÀ ThÀ PXZ) to two novel analogous materials, replacing the donor group by either acridine or phenothiazine. The emissive triplet excited state remains fixed in all three cases, while the emissive charge-transfer singlet states (and the calculated paired charge-transfer T 2 state) vary with the donor unit. While all three materials show dominant RTP in film, in solution different singlet-triplet and triplet-triplet energy gaps give rise to triplet-triplet annihilation followed by weak sRTP for the new compounds, compared to dominant sRTP throughout for the original PXZ material. Engineering both the sRTP state and higher charge-transfer states therefore emerges as a crucial element in designing emitters capable of sRTP.

show abstract

Section: Introductionmentioning

confidence: 99%

Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence

Paredis

Cardeynaels

Kuila

et al. 2023

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…A higher degree of charge transfer occurs by the synergistic interaction of the donor and the acceptor moieties, leading to the lowering of the singlet–triplet energy gap, i.e., ΔE ST . This is one of the key considerations in the development of TADF emitters . In this regard, azahelicenes that integrally incorporate a pyrrole ring have gained much interest, as they may feature a carbazole moiety; carbazoles are well-explored platforms in the development of OLED materials due to their high triplet energies, thermal stability, and excellent hole conducting properties. , Moreover, azahelicenes have also been reported to display significantly improved dissymmetry factors in CD and CPL spectra .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Excited-State Properties of Donor–Acceptor Azahelical Coumarins

et al. 2023

View full text Add to dashboard Cite

A set of three donor−acceptor azahelical coumarins (DA-AHCs), namely, H-AHC, Me-AHC, and Ph-AHC, were rationally designed and synthesized, and their excited-state properties were comprehensively investigated. All three DA-AHCs are shown to display very high fluorosolvatochromic shifts as a result of significant intramolecular charge transfer in their excited states. The para-quinoidal forms of the latter apparently contribute predominantly to large dipole moments in their excited states. By virtue of the fact that these helical systems structurally incorporate a highly fluorescent coumarin dye, they exhibit high quantum yields in both solution and solid states. Indeed, their emission behaviors in the crystalline media are shown to be remarkably correlated with their respective crystal packings. Incisive analyses demonstrate (i) strengthening of hydrogen bonding in the excited state promotes quenching (H-AHC), (ii) efficient crystal packing promotes high emission (Me-AHC) by precluding deactivations via vibrational motions, and (iii) loose crystal packing contributes to excited-state deactivation to account for low quantum yields of emission (Ph-AHC).

show abstract

“…However, 1,2,4-triazines possessing specific photophysical properties have seldom been used in optoelectrical research. Only a few 1,2,4-triazine derivatives have been employed as building blocks for organic photoactive materials, particularly organic light-emitting diodes [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. However, their closed nitrogen congeners (such as triazoles, pyrimidines, and s -triazines) are an inexhaustible source of numerous photoactive substances for various applications in optoelectronics and luminescent materials [ 19 , 20 , 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Isoxazolyl-Derived 1,4-Dihydroazolo[5,1-c][1,2,4]Triazines: Synthesis and Photochemical Properties

et al. 2023

View full text Add to dashboard Cite

New fluorescent dyes containing an assembled 1,4-dihydroazolo[5,1-c][1,2,4]triazine (DAT) core and an isoxazole ring were synthesized through a reaction between diazopyrazole or diazoimidazoles and isoxazolyl-derived enamines in mild conditions. The photophysical characteristics (maxima absorption and emission, Stokes shifts, fluorescent quantum yields, and fluorescence lifetimes) of the new fluorophores were obtained. The prepared DATs demonstrated emission maxima ranging within 433–487 nm, quantum yields within 6.1–33.3%, and a large Stokes shift. The photophysical characteristics of representative DAT examples were studied in ten different solvents. Specific (hydrogen bonds) and non-specific (dipole–dipole) intermolecular and intramolecular interactions were analyzed using XRD data and spectral experiments. Solvatochromism was analyzed using Lippert–Mataga and Dimroth–Reichardt plots, revealing the relationship between the DAT structure and the nature of solute–solvent interactions. The significant advantages of DATs are the fluorescence of their powders (QY up to 98.7%). DAT-NMe2 10 expressed bright aggregation-induced emission (AIE) behavior in DMSO and THF as the water content increased. The numerous possible variations of the structures of the heterocycles included in the DATs, as well as substituents, create excellent prospects for adjusting their photophysical and physicochemical properties.

show abstract

Novel D–A chromophores with condensed 1,2,4-triazine system simultaneously display thermally activated delayed fluorescence and crystallization-induced phosphorescence

Abstract: Control of photophysical properties is crucial for the continued development of electroluminescent devices and luminescent materials. Preparation and study of original molecules uncovers design rules towards efficient materials and devices....

Cited by 15 publications

References 73 publications

Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence

Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence

Synthesis and Excited-State Properties of Donor–Acceptor Azahelical Coumarins

Isoxazolyl-Derived 1,4-Dihydroazolo[5,1-c][1,2,4]Triazines: Synthesis and Photochemical Properties

Contact Info

Product

Resources

About