Electroluminescence based on thermally activated delayed fluorescence generated by a spirobifluorene donor–acceptor structure

Nakagawa, Tetsuya; Ku, Sung Yu; Wong, Ken‐Tsung; Adachi, Chihaya

doi:10.1039/c2cc31468a

Cited by 436 publications

(287 citation statements)

References 22 publications

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“…Organic semiconductors materials have been thoroughly used in the last decade for the development of a wide range of optoelectronic devices such as miniaturized organic field-effect transistors, [1][2][3][4] photovoltaic cells, [5][6][7] and organic light-emitting diodes, [8][9][10][11] commonly known as OLEDs. One of the most rich subfields within last years, for the purpose of having brighter and more efficient OLEDs for massive electronics, has been the study of new organic semiconductors showing electroluminescence.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Rationalization of the Singlet–Triplet Gap in OLEDs Materials: Impact of Charge-Transfer Character

Moral

Muccioli

Son

et al. 2014

J. Chem. Theory Comput.

128

143

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New materials for OLED applications with low singlet-triplet energy splitting have been recently synthesized in order to allow for the conversion of triplet into singlet excitons (emitting light) via a Thermally Activated Delayed Fluorescence (TADF) process, which involves excited-states with a non-negligible amount of Charge-Transfer (CT).The accurate modeling of these states with Time-Dependent Density Functional Theory (TD-DFT), the most used method so far because of the favorable trade-off between accuracy and computational cost, is however particularly challenging. We carefully address this issue here by considering materials with small (high) singlet-triplet gap acting as emitter (host) in OLEDs, and by comparing the accuracy of TD-DFT and the corresponding Tamm-Dancoff Approximation (TDA), which is found to greatly reduce error bars with respect to experiments thanks to better estimates for the lowest singlet-triplet transition. Finally, we quantitatively correlate the singlet-triplet splitting values with the extent of CT, using for it a simple metric extracted from calculations with double-hybrid functionals, that might be applied in further molecular engineering studies.

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Section: Introductionmentioning

confidence: 99%

Theoretical Rationalization of the Singlet–Triplet Gap in OLEDs Materials: Impact of Charge-Transfer Character

Moral

Muccioli

Son

et al. 2014

J. Chem. Theory Comput.

128

143

View full text Add to dashboard Cite

show abstract

“…Before Ar bubbling, the decay curve contained only a prompt component (intense peak) and no delayed component was found, suggesting that TADF is quenched by molecular oxygen dissolved in the solution. 26 This resulted in a low PLQY of 22%. In contrast, after Ar bubbling, a delayed component (long tail) was clearly observed, showing that triplet states of 3ACR-TRZ survive because of the removal of molecular oxygen from the solution.…”

mentioning

confidence: 99%

Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter

Wada

Shizu

Kubo

et al. 2015

Applied Physics Letters

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We developed a thermally activated delayed fluorescence (TADF) emitter, 2,4,6-tris(4-(9,9-dimethylacridan-10-yl)phenyl)-1,3,5-triazine (3ACR-TRZ), suitable for use in solution-processed organic light-emitting diodes (OLEDs). When doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host at 16 wt. %, 3ACR-TRZ showed a high photoluminescence quantum yield of 98%. Transient photoluminescence decay measurements of the 16 wt. % 3ACR-TRZ:CBP film confirmed that 3ACR-TRZ exhibits efficient TADF with a triplet-to-light conversion efficiency of 96%. This high conversion efficiency makes 3ACR-TRZ attractive as an emitting dopant in OLEDs. Using 3ACR-TRZ as an emitter, we fabricated a solution-processed OLED exhibiting a maximum external quantum efficiency of 18.6%.

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“…Other than the approaches just described, the modification of fluorene with the CN units followed by combination with donors could produce 10-phenyl-10H-spiro[acridine-9,9 -fluorene]-2 ,7 -dicarbonitrile (ACR-FLCN) and 2 ,7 -bis(di-p-tolylamino)-9,9 -spirobi[fluorene]-2,7-dicarbonitrile (spiro-CN) as green emitters [38][39][40]. The CN-modified fluorene was connected to the donor moieties through sp [3] carbon, which led to the complete separation of the HOMO and LUMO with a small overlap.…”

Section: Cyano (Cn)-modified Tadf Emittersmentioning

confidence: 99%

Recent progress of green thermally activated delayed fluorescent emitters

Lee

2017

Journal of Information Display

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Pure organic-based thermally activated delayed fluorescent (TADF) emitters have been studied for the last five years because of their potential as high-efficiency emitters comparable to phosphorescent emitters. Although the initial external quantum efficiency (EQE) of the TADF emitters was much lower than that of phosphorescent emitters, the current EQE of the TADF organic light-emitting diodes (OLEDs) is quite similar to that of phosphorescent OLEDs. In particular, the EQE of the green TADF OLEDs is already over 30% with the help of the new molecular design fully harvesting triplet excitons of the TADF emitters for light emission through the up-conversion process. In this work, the progress of the device performances of the TADF OLEDs was studied by reviewing the green TADF emitters that had been developed in the last five years. ARTICLE HISTORY

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Electroluminescence based on thermally activated delayed fluorescence generated by a spirobifluorene donor–acceptor structure

Abstract: An organic light emitting diode based on thermally activated delayed fluorescence (TADF) has been produced using a spirobifluorene derivative (Spiro-CN) having the donor-acceptor moieties as an emitter.

Cited by 436 publications

References 22 publications

Theoretical Rationalization of the Singlet–Triplet Gap in OLEDs Materials: Impact of Charge-Transfer Character

Theoretical Rationalization of the Singlet–Triplet Gap in OLEDs Materials: Impact of Charge-Transfer Character

Highly efficient electroluminescence from a solution-processable thermally activated delayed fluorescence emitter

Recent progress of green thermally activated delayed fluorescent emitters

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