Fluorene–Triphenylamine-Based Bipolar Materials: Fluorescent Emitter and Host for Yellow Phosphorescent OLEDs

Braveenth, Ramanaskanda; Jung, Hasu; Kim, Keunhwa; Kim, Bo Mi; Bae, Il-Ji; Kim, Miyoung; Chai, Kyu Yun

doi:10.3390/app10020519

Cited by 5 publications

(7 citation statements)

References 58 publications

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“…Among possible electron donating units, particular attention was devoted to triphenylamine ( TPA ), which is well known for its light-harvesting capabilities, high hole mobility properties, and non-coplanar structure preventing molecular aggregation [ 42 , 43 ]. Organic push-pull systems based on the TPA motive are of high importance for potential applications in solar-energy conversion [ 44 , 45 , 46 , 47 , 48 , 49 , 50 ] and as organic light-emitting diodes [ 51 , 52 , 53 , 54 ], logic gates [ 55 ], field-effect transistors [ 56 , 57 , 58 , 59 ] and photoswitches for theranostics [ 60 , 61 , 62 ]. In our previous contribution, we demonstrated the beneficial impact of the TPA unit on the luminescent properties of terpy and its Re(I) coordination compound [ 63 ].…”

Section: Introductionmentioning

confidence: 99%

Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive—Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties

Maroń

Cannelli²,

Socie³

et al. 2022

Molecules

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The introduction of an electron-donating triphenylamine motive into a 2,2′,6′,2′′-terpyridine (terpy) moiety, a cornerstone molecular unit in coordination chemistry, opens new ways for a rational design of photophysical properties of organic and inorganic compounds. A push-pull compound, 4′-(4-(di(4-tert-butylphenyl)amine)phenyl)-2,2′,6′,2′′-terpyridine (tBuTPAterpy), was thoroughly investigated with the use of steady-state and time-resolved spectroscopies and Density Functional Theory (DFT) calculations. Our results demonstrate that solvent parameters have an enormous influence on the optical properties of this molecule, acting as knobs for external control of its photophysics. The Intramolecular Charge Transfer (ICT) process introduces a remarkable solvent polarity effect on the emission spectra without affecting the lowest absorption band, as confirmed by DFT simulations, including solvation effects. The calculations ascribe the lowest absorption transitions to two singlet ICT excited states, S1 and S2, with S1 having several orders of magnitude higher oscillator strength than the “dark” S2 state. Temperature and viscosity investigations suggest the existence of two emitting excited states with different structural conformations. The phosphorescence emission band observed at 77 K is assigned to a localized 3terpy state. Finally, protonation studies show that tBuTPAterpy undergoes a reversible process, making it a promising probe of the pH level in the context of acidity determination.

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Section: Introductionmentioning

confidence: 99%

Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive—Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties

Maroń

Cannelli²,

Socie³

et al. 2022

Molecules

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“…Our simulations could successfully reproduce the experimental absorption spectrum which may indicate that our structural model is quite accurate. We can deduce this from the computed spectrum, since the applied LC-DFTB method very accurately reproduces the excitation energies of high-level quantum chemical methods as GW-BSE, CC2 or ADC (2). Further, the ground state structures have been sampled with DFTB, which shows a very good agreement for the molecular structures, particularly, for the BLA.…”

Section: Effects Of Aggregationmentioning

confidence: 86%

“…Nowadays, organic light-emitting diodes (OLEDs) have been considered as a new generation of technologies due to their high brightness, low-cost, low energy consumption, light weight and mechanical flexibility. [1][2][3][4] They can be used in many devices such as televisions, mobile phones, and other lighting resources. 5,6 Among different types of OLEDs, the phosphorescent OLEDs (PhOLEDs), serving as the second-generation OLEDs, have recently attracted much attention because they can generate light from both singlet and triplet states and thus allow the internal quantum efficiency to reach nearly 100%.…”

Section: Introductionmentioning

confidence: 99%

Understanding excited state properties of host materials in OLEDs: simulation of absorption spectrum of amorphous 4,4-bis(carbazol-9-yl)-2,2-biphenyl (CBP)

inanlou

Cortés-Mejía

Özdemir

et al. 2022

Phys. Chem. Chem. Phys.

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“…33−35 At the same time, D−A fluorescent emitters facilitate a large optical band gap, excellent thermal stability, structural robustness upon excitation, and enhanced device durability. 36 In addition, bipolar fluorescent emitters with a large triplet energy gap (E T ) are frequently applied as hosts in efficient phosphorescent OLEDs (PhOLEDs) as well as hybrid white OLEDs. 37−40 Under the triplet up-conversion mechanism, the IQE of a fluorescent molecule can exceed 25%; for example, IQE values of ∼65 and 100% have been realized through triplet−triplet annihilation (TTA) and hybridized local and charge-transfer states, respectively.…”

Section: Introductionmentioning

confidence: 99%

Multifaceted Sulfone–Carbazole-Based D–A–D Materials: A Blue Fluorescent Emitter as a Host for Phosphorescent OLEDs and Triplet–Triplet Annihilation Up-Conversion Electroluminescence

Yiu

Gnanasekaran

Chen

et al. 2022

ACS Appl. Mater. Interfaces

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Electroluminescence (EL) from the singlet-excited (S1) state is the ideal choice for stable, high-performing deep-blue organic light-emitting diodes (OLEDs) owing to the advantages of an adequately short radiative lifetime, improved device durability, and low cost, which are the most important criteria for their commercialization. Herein, we present the design and synthesis of three donor-acceptor-donor (D–A–D)-configured deep-blue fluorescent materials (denoted as TC–1, TC–2, and TC–3) composed of a thioxanthone or diphenyl sulfonyl acceptor and phenyl carbazolyl donor. These systems exhibit strong deep-blue photoluminescence (422–432 nm) in solutions and redshifted emission (472–486 nm) in thin films. The solid-state photoluminescence quantum yield (PLQY) was estimated to be 78 and 94% for TC–2 and TC–3, respectively. TC–2 and TC–3 possess good molecular packing and large molecular cross-sectional areas, which not only improves the PLQY but enhances the triplet–triplet annihilation up-conversion (TTAUC) efficiency of fluorescent emitters. Furthermore, both compounds were applied as an acceptor for confirming their TTAUC property using bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(III) (Ir(MDQ)2acac) as the sensitizer. Non-doped OLEDs based on TC–2 and TC–3 exhibit blue EL in the 461–476 nm range. In particular, TC–3 exhibits a maximum external quantum efficiency (EQEmax) of 5.1%, and its EL maximum is 476 nm. In addition, the three emitters were employed as hosts in red OLEDs using bis(1-phenylisoquinoline)(acetylacetonate)iridium(III) (Ir(piq)2acac) as the phosphorescent dopant. The red phosphorescent OLEDs based on TC–1, TC–2, and TC–3 achieve excellent EQEmax values of 21.6, 22.9, and 21.9%, respectively, and peak luminance efficiencies of 12.0, 14.0, and 12.3 cd A–1. These results highlight these fluorophores’ versatility and promising prospects in practical OLED applications.

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Fluorene–Triphenylamine-Based Bipolar Materials: Fluorescent Emitter and Host for Yellow Phosphorescent OLEDs

Cited by 5 publications

References 58 publications

Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive—Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties

Push-Pull Effect of Terpyridine Substituted by Triphenylamine Motive—Impact of Viscosity, Polarity and Protonation on Molecular Optical Properties

Understanding excited state properties of host materials in OLEDs: simulation of absorption spectrum of amorphous 4,4-bis(carbazol-9-yl)-2,2-biphenyl (CBP)

Multifaceted Sulfone–Carbazole-Based D–A–D Materials: A Blue Fluorescent Emitter as a Host for Phosphorescent OLEDs and Triplet–Triplet Annihilation Up-Conversion Electroluminescence

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