Radiationless transitions in electron donor-acceptor complexes: selection rules for S1 → T intersystem crossing and efficiency of S1 → S0 internal conversion

Lim, B. T.; Okajima, S.; Chandra, Asit K.; Lim, E. C.

doi:10.1016/0009-2614(81)85280-3

Cited by 93 publications

(107 citation statements)

References 7 publications

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“…[4][5][6][7][8][9] One way to improve the TADF emission contribution is to minimize the energy splitting (∆E ST ) between singlet and triplet states. Recent experimental studies [10][11][12] along with initial theoretical work [13][14][15] identify that the SOC mechanism in these TADF systems is a complex second order process requiring vibronic coupling between 3 CT and 3 LE to mediate the spin flip back to the 1 CT state, the 3 LE state mediates the SOC between the singlet and triplet CT states 15 . Hence whereas the CT states are very sensitive to the local enviroment 10 the local triplet states are not, therefore the host differential effects the energy gaps which directly changes the rate of reverse intersystem crossing (rISC).…”

Section: Toc Graphics Abstract Blue Oled Tadf Mechanism Charge Tranmentioning

confidence: 99%

Using Guest–Host Interactions To Optimize the Efficiency of TADF OLEDs

Santos

Ward

Bryce

et al. 2016

J. Phys. Chem. Lett.

258

264

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Section: Toc Graphics Abstract Blue Oled Tadf Mechanism Charge Tranmentioning

confidence: 99%

Using Guest–Host Interactions To Optimize the Efficiency of TADF OLEDs

Santos

Ward

Bryce

et al. 2016

J. Phys. Chem. Lett.

258

264

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“…Previous work has shown that in the one-electron approximation, intersystem crossing due to spin orbit coupling between the singlet charge transfer state ( 1 CT) and a locally triplet excited state ( 3 LE) is of fundamental importance to harvest triplet states, since the interconversion between the 1 CT and 3 CT states is often not efficient. 10,11 However, the presence of a local triplet energetically close to the CT manifold will strongly influence the efficiency of the TADF mechanism through charge transfer spin orbit coupling. Here, we explore the energy alignment between the CT manifold and a local triplet excited state in order to maximize the reverse intersystem crossing in a phenothiazine-dibenzothiophene-S,S-dioxide molecule, so this emitter can be used to design polymer materials showing efficient TADF emission in their pristine films.…”

Section: Introductionmentioning

confidence: 99%

“…1 However, this process is formerly forbidden for perpendicular HOMO and LUMO orbitals, which is the case in PTZ-DBTO2, due to unfavourable spin-orbit coupling (SOC) and Franck-Condon factors. 10,11,23 However, crossing between the 1 CT state and an energetically close local triplet state is efficient, as was shown by Dance et al 24 Hyperfine coupling (HFC) can in principle interconvert 1 CT to 3 CT and back. 25,26 However the exchange energy, i.e.…”

mentioning

confidence: 96%

Rational Design of TADF Polymers Using a Donor–Acceptor Monomer with Enhanced TADF Efficiency Induced by the Energy Alignment of Charge Transfer and Local Triplet Excited States

Nobuyasu

Ren

Griffiths

et al. 2016

Advanced Optical Materials

270

212

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. (2016) 'Rational design of TADF polymers using a donoracceptor monomer with enhanced TADF eciency induced by the energy alignment of charge transfer and local triplet excited states.', Advanced optical materials., 4 (4). pp. 597-607. Further information on publisher's website:http://dx.doi.org/10.1002/adom.201500689 Publisher's copyright statement: This is the peer reviewed version of the following article: Nobuyasu, R. S., Ren, Z., Griths, G. C., Batsanov, A. S., Data, P., Yan, S., Monkman, A. P., Bryce, M. R. and Dias, F. B. (2016) Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. performance with EQE of 22% at low luminance (<100 cd/m 2 ), for 100 cd/m 2 the EQE is 2 19.4%. In the case of solution processed devices, using the novel TADF polymers, the performance was much lower, EQE3.5% at 100 cd/m 2 , which is still the highest value for a polymer TADF system at useful brightness, yet reported. This results from a combination of weak charge transport properties in these materials and device fabrication methods that require further improvement. Nevertheless, these results pave the way to explore TADF in polymer light emitting diodes (PLEDs), using less costly deposition methods, such as spincoating and inkjet printing, which are more appropriate for large area deposition.

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“…Spin orbit coupling (SOC) for example is formally forbidden between singlet and triplet CT states for the case of near orthogonal D and A units, and thus the 1 CT state can only couple strongly to a close lying local triplet state. 13,14 The gap between these two states is thus the real ∆EST that requires thermal energy for triplets to cross over to the singlet state. These means that 1 CT can be either above or below the coupling triplet state for TADF to occur, but needs to be close to a local triplet state, so efficient SOC can occur.…”

Section: Introductionmentioning

confidence: 99%

Engineering the singlet–triplet energy splitting in a TADF molecule

et al. 2016

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The key to engineering an efficient TADF emitter is to achieve a small energy splitting between a pair of molecular singlet and triplet states. This work makes important contributions towards achieving this goal. By studying the new TADF emitter 2,7-bis(phenoxazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DPO-TXO2) and the donor and acceptor units separately, the available radiative and non-radiative pathways of DPO-TXO2 have been identified. The energy splitting between singlet and triplet states was clearly identified in four different environments, in solutions and solid state. The results show that DPO-TXO2 is a promising TADF emitter, having ∆EST = 0.01 eV in zeonex matrix. We further show how the environment plays a key role in the fine tuning of the energy levels of the 1 CT state with respect to the donor 3 LED triplet state, which can then be used to control the ∆EST energy value. We elucidate the TADF mechanism dynamics when the 1 CT state is located below the 3 LE triplet state which it spin orbit couples to, and we also discuss the OLED device performance with this new emitter, which shows maximum external quantum efficiency (E.Q.E) of 13.5% at 166 cd/m 2 .

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Radiationless transitions in electron donor-acceptor complexes: selection rules for S1 → T intersystem crossing and efficiency of S1 → S0 internal conversion

Cited by 93 publications

References 7 publications

Using Guest–Host Interactions To Optimize the Efficiency of TADF OLEDs

Using Guest–Host Interactions To Optimize the Efficiency of TADF OLEDs

Rational Design of TADF Polymers Using a Donor–Acceptor Monomer with Enhanced TADF Efficiency Induced by the Energy Alignment of Charge Transfer and Local Triplet Excited States

Engineering the singlet–triplet energy splitting in a TADF molecule

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