Asymmetric-donor (D<sub>2</sub>D<sub>2</sub>′)–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF

Bhatia, Harsh; Ray, Debdas

doi:10.1039/d0ma00382d

Cited by 16 publications

(23 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Phosphorescent materials obtained by coupling difluoride dibenzoylmethane with poly(lactic acid) were developed in 2007, where green phosphorescence with a lifetime of 170 ms was achieved under vacuum conditions, and the afterglow can last about 2 s after removing the excitation . Later, efficient RTP materials were explored based on poly(methyl methacrylate) (PMMA) and poly(vinyl alcohol) (PVA) matrices. − For instance, Kim et al doped 2,5-dihexyloxy-4-bromobenzaldehyde and 2,2′-((2-bromo-5-formyl-1,4-phenylene)bis(oxy))diacetic acid into PMMA or PVA to realize efficient RTP. , Ogoshi and coworkers reported long RTP with a maximum phosphorescence lifetime of 1221 ms from poly(styrene sulfonic acid) in the solid state, and the afterglow duration time reached 2.2 s after the excitation. An important class of copolymers prepared from acrylamide was reported by Tian, Ma, and coworkers .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

et al. 2021

View full text Add to dashboard Cite

Polymer-based room-temperature phosphorescence (RTP) materials with high flexibility and large-area producibility are highly promising for applications in organic electronics. However, achieving such photophysical materials is challenging because of difficulties in populating and stabilizing susceptible triplet excited states at room temperature. Herein large-area, flexible, transparent, and long-lived RTP systems prepared by doping rationally selected organic chromophores in a poly(vinyl alcohol) (PVA) matrix were realized through a hydrogen-bonding and coassembly strategy. In particular, the 3,6-diphenyl-9H-carbazole (DPCz)-doped PVA film shows long-lived phosphorescence emission (up to 2044.86 ms) and a remarkable duration of afterglow (over 20 s) under ambient conditions. Meanwhile, the 7H-dibenzo[c,g]carbazole (DBCz)-doped PVA film exhibits high absolute luminance of 158.4 mcd m2 after the ultraviolet excitation source is removed. The RTP results not only from suppressing the nonradiative decay by abundant hydrogen-bonding interactions in the PVA matrix but also from minimizing the energy gap (ΔE ST) between the singlet state and the triplet state through the coassembly effect. On account of the outstanding mechanical properties and the afterglow performance of these RTP materials, they were applied in the fabrication of flexible 3D objects with repeatable folding and curling properties. Importantly, the multichannel afterglow light-emitting diode arrays were established under ambient conditions. The present long-lived phosphorescent systems demonstrate a bright opportunity for the production of large-area, flexible, and transparent emitting materials.

show abstract

Section: Introductionmentioning

confidence: 99%

“…Development of RTP materials and a strategy to achieve efficient RTP. (a) Milestones of RTP materials from years 2007 to 2020 (referring to the refs − ). (b) Feasible strategy to achieve a long-lived RTP system by doping the heterocyclic polynuclear aromatic compound DPCz into the PVA matrix.…”

Section: Introductionmentioning

confidence: 99%

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In this study, we propose a method for calculating the radiative decay rate of a TADF emitter by including the vibronic coupling effects between excited states. We demonstrate the utility of the method by computing the fluorescence rates of carbazolyl-phthalonitrile (CzPN) derivatives, as they have been widely studied as candidate TADF materials ,− (for the chemical structures of the adopted CzPN derivatives, see Figure ). By comparing the fluorescence rates with and without the couplings with higher-lying excited states, we discuss the significance of the vibronic effects in characterizing fluorescence from the TADF molecules.…”

Section: Introductionmentioning

confidence: 99%

Effect of Perturbative Vibronic Correction for Weak Fluorescence in Thermally Activated Delayed Fluorescence Systems

et al. 2020

View full text Add to dashboard Cite

Minimizing the energy difference between the lowest singlet (S 1 ) and the lowest triplet states, ΔE ST , is the main strategy to design thermally activated delayed fluorescence (TADF) molecules, and spatially separating the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is the general method in the design. However, such a separation also tends to reduce the oscillator strength of the S 1 state. In real systems, vibrations change the S 1 oscillator strength, and thus one needs to consider the vibronic coupling toward searching for TADF candidate molecules. Here, we evaluate the importance of vibronic coupling by including the first-order perturbative correction to the transition dipole moments of carbazolyl-phthalonitrile derivatives. Indeed, some molecules display large enhancements in their oscillator strengths, with their fluorescence lifetimes reduced by 2 orders of magnitude. The twisting mode between the carbazole groups and phthalonitrile is the most important mode in inducing the perturbations. Thus, performing the perturbative correction is crucial in attaining more reliable predictions on their fluorescence propensities. We also observe that some other molecules, whose zeroth-order predicted fluorescence rates are much slower than the actual experimental data, are affected little by the same first-order correction. For these molecules, we deduce that the geometry-dependent excited-state switching kicks in. Our results demonstrate the significance of vibronic coupling in TADF molecules and the importance of adopting correction schemes as the guidelines for screening of useful TADF molecules.

show abstract

“…All the compounds exhibit higher energy absorption bands at 265 and 311 nm which can be attributed to the π → π* transition. 34 , 35 , 50 , 51 In addition, a broad tail ranging from ∼355 to 500 nm which shows a slight hypsochromic shift upon increasing solvent polarity, was observed. A comparison between the absorption spectra of D (Phx) and A (QPP) fragments with all the conjugates confirms that a higher energy region of the absorption spectra of the D–A conjugates arises due to the arithmetic sum of the D and A absorption spectra, while the appearance of lower energy broad absorption bands (ε = 6100–7100 L·mol –1 ·cm –1 ) is due to the charge transfer (CT) caused by D–A torsion ( Figure 4 ), which is conducive for visible light excitation (VLE).…”

Section: Results and Discussionmentioning

confidence: 96%

“…Similar emission dynamics were also observed in bis[2-(di(phenyl)phosphino)-phenyl]ether oxide (DPEPO) (0.1 wt %), except a significant bathochromic shift of the lower energy broad emission bands (520, 530, 541 nm) was measured due to increased polarity of the host material ( Figures S31, S32 ). 35 The phosphorescence lifetimes of the conjugates (PQ: τ 1 = 64 ms, τ 2 = 130.3 ms. PQCl: τ 1 = 84.39 ms, τ 2 = 200.56 ms. PQBr: τ 1 = 8.46 ms, τ 2 = 37.71 ms) further ensure that the 3 CT state contributes for RTP of all the conjugates at ambient conditions ( Figures S31, S32 ). The longer lifetimes of the triplet states in DPEPO as compared with the Zeonex films can be explained by the stabilization of the triplet excitons caused by a more polar host.…”

Section: Results and Discussionmentioning

confidence: 99%

Phenoxazine–Quinoline Conjugates: Impact of Halogenation on Charge Transfer Triplet Energy Harvesting via Aggregate Induced Phosphorescence

et al. 2022

Self Cite

View full text Add to dashboard Cite

Room-temperature phosphorescence (RTP) from organic compounds has attracted increasing attention in the field of data security, sensing, and bioimaging. However, realization of RTP with an aggregate induced phosphorescence (AIP) feature via harvesting supersensitive excited charge transfer triplet ( 3 CT) energy under visible light excitation (VLE) in single-component organic systems at ambient conditions remains unfulfilled. Organic donor–acceptor (D–A) based orthogonal structures can therefore be used to harvest the energy of the 3 CT state at ambient conditions under VLE. Here we report three phenoxazine–quinoline conjugates (PQ, PQCl, PQBr), in which D and A parts are held in orthogonal orientation around the C–N single bond; PQCl and PQBr are substituted with halogens (Cl, Br) while PQ has no halogen atom. Spectroscopic studies and quantum chemistry calculations combining reference compounds (Phx, QPP) reveal that all the compounds in film at ambient conditions show fluorescence and green-RTP due to (i) radiative decay of both singlet charge transfer ( 1 CT) and triplet CT ( 3 CT) states under VLE, (ii) energetic nondegeneracy of 1 CT and 3 CT states ( 1 CT– 3 CT, 0.17–0.21 eV), and (iii) spatial separation of highest and lowest unoccupied molecular orbitals. Further, we found in a tetrahydrofuran–water mixture ( f w = 90%, v/v) that both PQCl (10 –5 M) and PQBr (10 –5 M) show concentration-dependent AIP with phosphorescence quantum yields (ϕ P ) of ∼25% and ∼28%, respectively, whereas aggregate induced quenching (ACQ) was observed in PQ. The phosphorescence lifetimes (τ P ) of the PQCl and PQBr aggregates were shown to be ∼22–62 μs and ∼22–59 μs, respectively. The ϕ P of the powder samples is found to be 0.03% (PQ), 15.6% (PQCl), and 13.0% (PQBr), which are significantly lower than that of the aggregates (10 –5 M, f w = 90%, v/v). Film (Zeonex, 0.1 wt %) studies revealed that ϕ P of PQ (7.1%) is relatively high, while PQCl and PQBr exhibit relatively low ϕ P values (PQCl, 9.7%; PQBr, 8.8%), as compared with that of powder samples. In addition, we found in single-crystal X-ray analysis that multiple noncovalent interactions along with halogen···halogen (Cl···Cl) interactions between the neighboring molecules play an important role to stabilize the 3 CT caused by increased rigidity of the molecular backbone. This design principle reveals a method to understand nondegeneracy of 1 CT and 3 CT states, and RTP with a concentration-dependent AIP effect using halogen substituted twisted donor–acceptor conju...

show abstract

Asymmetric-donor (D₂D₂′)–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF

Abstract: Developing new photoluminescent (PL) materials with simultaneous room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) features is highly desirable for bio-imaging, security applications and sensors due to the involvement...

Cited by 16 publications

References 49 publications

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

Effect of Perturbative Vibronic Correction for Weak Fluorescence in Thermally Activated Delayed Fluorescence Systems

Phenoxazine–Quinoline Conjugates: Impact of Halogenation on Charge Transfer Triplet Energy Harvesting via Aggregate Induced Phosphorescence

Contact Info

Product

Resources

About

Asymmetric-donor (D2D2′)–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF

Abstract: Developing new photoluminescent (PL) materials with simultaneous room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) features is highly desirable for bio-imaging, security applications and sensors due to the involvement...

Cited by 16 publications

References 49 publications

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films

Effect of Perturbative Vibronic Correction for Weak Fluorescence in Thermally Activated Delayed Fluorescence Systems

Phenoxazine–Quinoline Conjugates: Impact of Halogenation on Charge Transfer Triplet Energy Harvesting via Aggregate Induced Phosphorescence

Contact Info

Product

Resources

About

Asymmetric-donor (D₂D₂′)–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF