All-organic fast intersystem crossing assisted exciplexes exhibiting sub-microsecond thermally activated delayed fluorescence

Traskovskis, Kaspars; Sebris, Armands; Novosjolova, Irina; Turks, Māris; Gužauskas, Matas; Volyniuk, Dmytro; Bezvikonnyi, Oleksandr; Mishnev, Anatoly; Gržibovskis, Raitis; Vembris, Aivars

doi:10.1039/d0tc05099g

Cited by 23 publications

(25 citation statements)

References 54 publications

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“…They practically have only delayed fluorescence components. 40 We suppose that such sub-microsecond TADF of 5b was observed due to the efficient population of 3 LE A via the ISC process and due to the similarity of 3 LE A and 1 CT energy levels allowing efficient RISC. The mechanism of sub-microsecond TADF is not much discussed here since it was well described earlier.…”

Section: Results and Discussionmentioning

confidence: 94%

“…The mechanism of sub-microsecond TADF is not much discussed here since it was well described earlier. 40 It is worth to note that compounds 5a , 5b , and 5c can show combination of both conventional and sub-microsecond TADF. The most efficient sub-microsecond TADF was observed for compound 5b because its 1 CT level is closer to the 3 LE A level ( Figures 5 b and 6 a).…”

Section: Results and Discussionmentioning

confidence: 97%

“…Such or even much stronger shifts are typical for donor–acceptor compounds due to the ICT nature of their emission. 40 Compound 5c containing two carbazole units was characterized by additional emission band in the UV region which can be assigned to recombination of local excited (LE) states of the carbazole moiety. LE nature of this additional band is evident because PhCz was characterized by emission by the similar PL spectrum ( Figure 5 a).…”

Section: Results and Discussionmentioning

confidence: 99%

“…In addition, the energy of local excited triplet states, 3 LE A was practically the same as that of the intermolecular charge transfer state 1 CT of exciplex systems (solid-state mixture of triazole and PhCz) which predetermines the efficient RISC pathway 3 LE A → 1 CT of covalently-bonded exciplex-forming systems 5a – 5c as it was previously demonstrated for PCP-based exciplex systems. 40 …”

Section: Results and Discussionmentioning

confidence: 99%

“…When a 6-cyano-9-phenylpurine (PCP) acceptor unit was linked to a carbazole-based donor unit, the obtained exciplex-forming compounds with covalently bonded donor and acceptor moieties demonstrated sub-microsecond TADF with delayed-only emission and high reverse intersystem crossing (RISC) rates exceeding 10 7 s –1 . 40 Such fast and efficient intersystem crossing (ISC) was achieved due to highly efficient population of a local excited triplet state ( 3 LE A ) of PCP from the singlet state 1 LE A of the acceptor (PCP). The locally excited triplet state 3 LE A provides an efficient RISC pathway ( 3 LE A → 1 CT) between the excited singlet intermolecular charge transfer state ( 1 CT) of the PCP-based exciplex systems.…”

Section: Introductionmentioning

confidence: 99%

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Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

et al. 2022

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Using the newly designed exciplex-forming 1,2,3-triazole-based acceptors with fast and efficient singlet → triplet intersystem crossing (ISC) processes, carbazole and benzoyl-1 H -1,2,3-triazole derivatives were synthesized by Dimroth-type 1,2,3-triazole ring formation and Ullmann–Goldberg C–N coupling reactions. Due to the exciplex formation between covalently bonded electron-donating (carbazole) and 1,2,3-triazole-based electron-accepting moieties with small singlet-triplet splitting (0.07–0.13 eV), the compounds exhibited ISC-assisted bluish–green thermally activated delayed fluorescence. The compounds were characterized by high triplet energy levels ranging from 2.93 to 2.98 eV. The most efficient exciplex-type thermally activated delayed fluorescence was observed for ortho-substituted carbazole-benzoyl-1 H -1,2,3-triazole which was selected as a host in the structure of efficient solution-processed white light-emitting diodes. The best device exhibited a maximum power efficiency of 10.7 lm/W, current efficiency of 18.4 cd/A, and quantum efficiency of 7.1%. This device also showed the highest brightness exceeding 10 thousand cd/m 2 . Usage of the exciplex-forming host allowed us to achieve a low turn-on voltage of 3.6 V. High-quality white electroluminescence was obtained with the close to nature white color coordinates (0.31, 0.34) and a color rendering index of 92.

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Section: Results and Discussionmentioning

confidence: 94%

Section: Results and Discussionmentioning

confidence: 97%

Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

et al. 2022

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Photophysical Properties of Boron‐Based Chromophores as Effective Moieties in TADF Devices: A Computational Study**

Ulukan,

Monari,

Catak

2023

ChemPhotoChem

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Thermally activated delayed fluorescence (TADF) materials have shown great potential in the design of organic metal‐free optoelectronic devices and materials and, therefore, are the subject of intense investigations. This contribution presents the effects of various parameters on the photophysical properties of a series of Boron‐based TADF emitters. These include torsion angle, the changes in the electronic density, energy gap between the first excited singlet (S1) and the first excited triplet states (T1), oscillator strength (f) and spin–orbit coupling (SOC). Through a comprehensive structural analysis, we firstly show the most favorable conformation of the ground state of donor (D) and acceptor (A) moieties that are popular in TADF emitters. Further, the properties of the excited state manifolds are obtained with Tamm‐Dancoff Approximation (TDA), thus rationalizing their optical and photophysical properties. Globally, our results settle the basis for the rationalization of the effects of different parameters on reverse intersystem crossing (RISC) probabilities, which is the rate‐limiting step for TADF, thus favoring the rational design of novel highly efficient TADF materials with strong triplet exciton harvesting.

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Boron‐Based Multi‐Resonance TADF Emitter with Suppressed Intermolecular Interaction and Isomer Formation for Efficient Pure Blue OLEDs

Cheon

Shin

Park

et al. 2022

Small

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Multi‐resonance (MR) thermally activated delayed fluorescent (TADF) emitters are highly attractive due to their superior color purity as well as efficient light‐harvesting ability from singlets and triplets. However, boron and nitrogen‐based MR‐TADF emitters suffer from their strong π–π interaction owing to their rigid flat cores. Herein, a boron‐based multi‐resonance blue TADF emitter with suppressed intermolecular interaction and isomer formation is developed through a simple synthetic process by introducing meta‐xylene and meta‐phenyphenyl groups to the core. The MR‐TADF emitter, mBP‐DABNA‐Me, shows a narrowband blue emission with a peak at 467 nm, along with full width at half maximum of 28 nm, and photoluminescence quantum yield of 97%. Notably, highly efficient pure blue organic light‐emitting diode (OLED) is realized using mBP‐DABNA‐Me, showing a maximum external quantum efficiency of 24.3% and a stable blue emission with a Commission Internationale de L'Eclairage coordinate of (0.124, 0.140). The color purity of the OLED is maintained at a high doping concentration of over 20%, attributed to the suppressed intermolecular interaction between the MR emitters.

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All-organic fast intersystem crossing assisted exciplexes exhibiting sub-microsecond thermally activated delayed fluorescence

Abstract: Molecules with fast intersystem crossing characteristics can be used as components for sub-microsecond TADF exciplexes.

Cited by 23 publications

References 54 publications

Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

Exciplex-Forming Systems of Physically Mixed and Covalently Bonded Benzoyl-1H-1,2,3-Triazole and Carbazole Moieties for Solution-Processed White OLEDs

Photophysical Properties of Boron‐Based Chromophores as Effective Moieties in TADF Devices: A Computational Study**

Boron‐Based Multi‐Resonance TADF Emitter with Suppressed Intermolecular Interaction and Isomer Formation for Efficient Pure Blue OLEDs

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