المؤلفون: Wang, Tao, Gupta, Abhishek Kumar, Cordes, David B., Slawin, Alexandra M. Z., Zysman-Colman, Eli

المصدر: Wang , T , Gupta , A K , Cordes , D B , Slawin , A M Z & Zysman-Colman , E 2023 , ' Reducing efficiency roll-off in multi-resonant thermally activated delayed fluorescent OLEDs through modulation of the energy of the T 2 state ' , Advanced Optical Materials , vol. 11 , no. 10 , 2300114 . https://doi.org/10.1002/adom.202300114Test

مصطلحات موضوعية: Multi-resonant thermally activated delayed fluorescence (MR-TADF), Emissive T2 state, Narrowband emission, Conjugation modulation, Organic light emitting diodes

الوصف: The S 1 state and high-lying triplet excited states (ΔE S1Tn ) offer insight into clarifying the mechanism of efficiency roll-off of organic light-emitting diodes (OLEDs). However, experimental detection of the ΔE S1Tn is challenging due to Kasha's rule. Here, two emitters, PhCz-O-DiKTa and PhCz-DiKTa , showing multi-resonant thermally activated delayed fluorescence (MR-TADF) are reported. By modulating the conjugation between the MR-TADF DiKTa emissive center and donor substituent, emission directly from the T 2 state is for the first time observed in MR-TADF emitters. Single crystal and reduced density gradient analyses reveal the origin of the reduced observed concentration-quenching results from weak CH···π and slipped π···π stacking interactions, which suppress nonradiative transitions. Theoretical and photophysical investigations reveal that the ΔE S1T2 difference influences the reverse intersystem crossing rate. The OLEDs employing PhCz-O-DiKTa and PhCz-DiKTa as emitters show maximum external quantum efficiencies (EQE max ) of over 20%, but very different efficiency roll-off behavior (54.5% vs 13.6% at 100 cd m −2 ). Thus, this design provides a possible solution to mitigating device efficiency roll-off by designing MR-TADF emitters with degenerate S 1 and T 2 states.

وصف الملف: application/pdf

العلاقة: https://research-portal.st-andrews.ac.uk/en/researchoutput/reducing-efficiency-rolloff-in-multiresonant-thermally-activated-delayed-fluorescent-oleds-through-modulation-of-the-energy-of-the-t2-stateTest(48f7810d-a6e5-47bd-ad9d-fd285ce2ddad).html

الإتاحة: https://doi.org/10.1002/adom.202300114Test
https://research-portal.st-andrews.ac.uk/en/researchoutput/reducing-efficiency-rolloff-in-multiresonant-thermally-activated-delayed-fluorescent-oleds-through-modulation-of-the-energy-of-the-t2-stateTest(48f7810d-a6e5-47bd-ad9d-fd285ce2ddad).html
https://research-repository.st-andrews.ac.uk/bitstream/10023/27220/1/Wang_2023_Reducing_efficiency_roll_off_AdvOpticMat_202300114_CCBY.pdfTest

المؤلفون: Hall, David, Suresh, Subeesh Madayanad, dos Santos, Paloma L., Duda, Eimantas, Bagnich, Sergey, Pershin, Anton, Rajamalli, Pachaiyappan, Cordes, David B., Slawin, Alexandra M.Z., Beljonne, David, Köhler, Anna, Samuel, Ifor D.W., Olivier, Yoann, Zysman-Colman, Eli

المصدر: Hall , D , Suresh , S M , dos Santos , P L , Duda , E , Bagnich , S , Pershin , A , Rajamalli , P , Cordes , D B , Slawin , A M Z , Beljonne , D , Köhler , A , Samuel , I D W , Olivier , Y & Zysman-Colman , E 2020 , ' Improving Processability and Efficiency of Resonant TADF Emitters : A Design Strategy ' , Advanced Optical Materials , vol. 8 , no. 2 , 1901627 . https://doi.org/10.1002/adom.201901627Test

مصطلحات موضوعية: blue emission, multiresonance thermally activated delayed fluorescence, organic light emitting diodes, SCS-CC2 approach

الوصف: A new design strategy is introduced to address a persistent weakness with resonance thermally activated delayed fluorescence (R-TADF) emitters to reduce aggregation-caused quenching effects, which are identified as one of the key limiting factors. The emitter Mes 3 DiKTa shows an improved photoluminescence quantum yield of 80% compared to 75% for the reference DiKTa in 3.5 wt% 1,3-bis(N-carbazolyl)benzene. Importantly, emission from aggregates, even at high doping concentrations, is eliminated and aggregation-caused quenching is strongly curtailed. For both molecules, triplets are almost quantitatively upconverted into singlets in electroluminescence, despite a significant (≈0.21 eV) singlet-triplet energy gap (ΔE ST ), in line with correlated quantum-chemical calculations, and a slow reverse intersystem crossing. It is speculated that the lattice stiffness responsible for the narrow fluorescence and phosphorescence emission spectra also protects the triplets against nonradiative decay. An improved maximum external quantum efficiencies (EQE max ) of 21.1% for Mes 3 DIKTa compared to the parent DiKTa (14.7%) and, importantly, reduced efficiency roll-off compared to literature resonance TADF organic light-emitting diodes (OLEDs), shows the promise of this design strategy for future design of R-TADF emitters for OLED applications.

وصف الملف: application/pdf

العلاقة: https://researchportal.unamur.be/en/publications/a0c7dc6e-39b7-4a22-ac2c-b5de876f4755Test

الإتاحة: https://doi.org/10.1002/adom.201901627Test
https://researchportal.unamur.be/en/publications/a0c7dc6e-39b7-4a22-ac2c-b5de876f4755Test
https://pure.unamur.be/ws/files/52079346/2020_OlivierY_article.pdfTest
http://www.scopus.com/inward/record.url?scp=85076107915&partnerID=8YFLogxKTest

المؤلفون: Si, Changfeng, Wang, Tao, Gupta, Abhishek Kumar, Cordes, David B., Slawin, Alexandra M. Z., Siegel, Jay S., Zysman‐Colman, Eli

المصدر: Angewandte Chemie; 10/23/2023, Vol. 135 Issue 43, p1-12, 12p

مصطلحات موضوعية: ORGANIC light emitting diodes, LIGHT emitting diodes, SOLAR energy, QUANTUM efficiency, SOLAR cells, CORANNULENE, PHOSPHORESCENCE, SURFACE plasmon resonance

مستخلص: Corannulene‐derived materials have been extensively explored in energy storage and solar cells, however, are rarely documented as emitters in light‐emitting sensors and organic light‐emitting diodes (OLEDs), due to low exciton utilization. Here, we report a family of multi‐donor and acceptor (multi‐D‐A) motifs, TCzPhCor, TDMACPhCor, and TPXZPhCor, using corannulene as the acceptor and carbazole (Cz), 9,10‐dihydro‐9,10‐dimethylacridine (DMAC), and phenoxazine (PXZ) as the donor, respectively. By decorating corannulene with different donors, multiple phosphorescence is realized. Theoretical and photophysical investigations reveal that TCzPhCor shows room‐temperature phosphorescence (RTP) from the lowest‐lying T1; however, for TDMACPhCor, dual RTP originating from a higher‐lying T1 (T1H) and a lower‐lying T1 (T1L) can be observed, while for TPXZPhCor, T1H‐dominated RTP occurs resulting from a stabilized high‐energy T1 geometry. Benefiting from the high‐temperature sensitivity of TPXZPhCor, high color‐resolution temperature sensing is achieved. Besides, due to degenerate S1 and T1H states of TPXZPhCor, the first corannulene‐based solution‐processed afterglow OLEDs is investigated. The afterglow OLED with TPXZPhCor shows a maximum external quantum efficiency (EQEmax) and a luminance (Lmax) of 3.3 % and 5167 cd m−2, respectively, which is one of the most efficient afterglow RTP OLEDs reported to date. [ABSTRACT FROM AUTHOR]

: Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Wang, Tao, Gupta, Abhishek Kumar, Cordes, David B., Slawin, Alexandra M. Z., Zysman‐Colman, Eli

المساهمون: European Commission, EPSRC, University of St Andrews. School of Chemistry, University of St Andrews. Institute of Behavioural and Neural Sciences, University of St Andrews. EaSTCHEM, University of St Andrews. Centre for Energy Ethics

مصطلحات موضوعية: MCC, Emissive T2 state, Narrowband emission, DAS, QD, Conjugation modulation, Multi-resonant thermally activated delayed fluorescence (MR-TADF), Organic light emitting diodes, QD Chemistry, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials

الوصف: Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No. 897098 (AIE-RTP-PLED). T.W. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship. The auhors thank the EPSRC (EP/R035164/1) for financial support. The S1 state and high-lying triplet excited states (ΔES1Tn) offer insight into clarifying the mechanism of efficiency roll-off of organic light-emitting diodes (OLEDs). However, experimental detection of the ΔES1Tn is challenging due to Kasha's rule. Here, two emitters, PhCz-O-DiKTa and PhCz-DiKTa , showing multi-resonant thermally activated delayed fluorescence (MR-TADF) are reported. By modulating the conjugation between the MR-TADF DiKTa emissive center and donor substituent, emission directly from the T2 state is for the first time observed in MR-TADF emitters. Single crystal and reduced density gradient analyses reveal the origin of the reduced observed concentration-quenching results from weak CH···π and slipped π···π stacking interactions, which suppress nonradiative transitions. Theoretical and photophysical investigations reveal that the ΔES1T2 difference influences the reverse intersystem crossing rate. The OLEDs employing PhCz-O-DiKTa and PhCz-DiKTa as emitters show maximum external quantum efficiencies (EQEmax) of over 20%, but very different efficiency roll-off behavior (54.5% vs 13.6% at 100 cd m−2). Thus, this design provides a possible solution to mitigating device efficiency roll-off by designing MR-TADF emitters with degenerate S1 and T2 states. Publisher PDF

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d9e7907fbac10fb155880fe411eb1addTest
https://hdl.handle.net/10023/27220Test

المؤلفون: Wang, Tao, Gupta, Abhishek Kumar, Cordes, David B., Slawin, Alexandra M. Z., Zysman‐Colman, Eli

المصدر: Advanced Optical Materials; 5/19/2023, Vol. 11 Issue 10, p1-10, 10p

مصطلحات موضوعية: ORGANIC light emitting diodes, DELAYED fluorescence, LIGHT emitting diodes, ENERGY policy, STACKING interactions, QUANTUM efficiency

مستخلص: The S1 state and high‐lying triplet excited states (ΔES1Tn) offer insight into clarifying the mechanism of efficiency roll‐off of organic light‐emitting diodes (OLEDs). However, experimental detection of the ΔES1Tn is challenging due to Kasha's rule. Here, two emitters, PhCz‐O‐DiKTa and PhCz‐DiKTa, showing multi‐resonant thermally activated delayed fluorescence (MR‐TADF) are reported. By modulating the conjugation between the MR‐TADF DiKTa emissive center and donor substituent, emission directly from the T2 state is for the first time observed in MR‐TADF emitters. Single crystal and reduced density gradient analyses reveal the origin of the reduced observed concentration‐quenching results from weak CH···π and slipped π···π stacking interactions, which suppress nonradiative transitions. Theoretical and photophysical investigations reveal that the ΔES1T2 difference influences the reverse intersystem crossing rate. The OLEDs employing PhCz‐O‐DiKTa and PhCz‐DiKTa as emitters show maximum external quantum efficiencies (EQEmax) of over 20%, but very different efficiency roll‐off behavior (54.5% vs 13.6% at 100 cd m−2). Thus, this design provides a possible solution to mitigating device efficiency roll‐off by designing MR‐TADF emitters with degenerate S1 and T2 states. [ABSTRACT FROM AUTHOR]

: Copyright of Advanced Optical Materials is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Wong, Michael Yin, Krotkus, Simonas, Copley, Graeme, Li, Wenbo, Murawski, Caroline, Hall, David, Hedley, Gordon, Jaricot, Marie, Cordes, David B., Slawin, Alexandra M. Z., Olivier, Yoann, Beljonne, David, Muccioli, Luca, Moral, Mónica, Sancho-García, Juan Carlos, Gather, Malte C, Samuel, Ifor D. W., Zysman-Colman, Eli

المصدر: Wong , M Y , Krotkus , S , Copley , G , Li , W , Murawski , C , Hall , D , Hedley , G , Jaricot , M , Cordes , D B , Slawin , A M Z , Olivier , Y , Beljonne , D , Muccioli , L , Moral , M , Sancho-García , J C , Gather , M C , Samuel , I D W & Zysman-Colman , E 2018 , ' Deep blue oxadiazole-containing thermally activated delayed fluorescence emitters for organic light-emitting diodes ' , ACS Applied Materials ....

مصطلحات موضوعية: Thermally activated delayed fluorescence, Organic light emitting diodes, Oxadiazoles, Blue emitters, DFT calculations

الوصف: A series of four novel deep blue to sky blue thermally activated delayed fluorescence (TADF) emitters (2CzdOXDMe, 2CzdOXD4MeOPh, 2CzdOXDPh and 2CzdOXD4CF 3 Ph) have been synthesized and characterized. These oxadiazole-based emitters demonstrated bluer emission compared with reference emitter 2CzPN thanks to the weaker acceptor strength of oxadiazole moieties. In particular, the oxadiazole compounds doped in hosts (mCP and PPT) emitted from 435-474 nm with photoluminescence quantum yields ranging from 14%-55%. The emitters possess relatively large singlet-triplet excited state energy gaps (ΔEST) from 0.25-0.46 eV resulting in long lifetimes of the delayed components ranging from 4.8 to 25.8 ms. Electroluminescent devices using these oxadiazole emitters as dopant emitters gave emission maxima (λEL) from 446 nm to 474 nm with maximum external quantum efficiencies ranging from 4.2-11.2%.

وصف الملف: application/pdf

العلاقة: https://research-portal.st-andrews.ac.uk/en/researchoutput/deep-blue-oxadiazolecontaining-thermally-activated-delayed-fluorescence-emitters-for-organic-lightemitting-diodesTest(bfac0ac4-4564-4da8-9f94-e28077839dbb).html

الإتاحة: https://doi.org/10.1021/acsami.8b11136Test
https://research-portal.st-andrews.ac.uk/en/researchoutput/deep-blue-oxadiazolecontaining-thermally-activated-delayed-fluorescence-emitters-for-organic-lightemitting-diodesTest(bfac0ac4-4564-4da8-9f94-e28077839dbb).html
https://research-repository.st-andrews.ac.uk/bitstream/10023/18433/1/Wong_2018_ACSMI_Deepblue_AAM.pdfTest

المؤلفون: Mackenzie, Campbell F. R., Zhang, Le, Cordes, David B., Slawin, Alexandra M. Z., Samuel, Ifor D.W., Zysman‐Colman, Eli

المصدر: Advanced Optical Materials; Jan2023, Vol. 11 Issue 2, p1-14, 14p

مصطلحات موضوعية: ORGANIC light emitting diodes, IRIDIUM, ANTHRACENE derivatives, LIGHT emitting diodes, QUANTUM efficiency, INTERMOLECULAR interactions, ISOMERS

مستخلص: Four new deep‐blue‐emitting iridium(III) NHC complexes containing sterically demanding ligands are synthesized. The four complexes show bright, deep‐blue emission, with emission maxima between 420 and 427 nm in both acetonitrile solution and 30 wt% doped films in TSPO1; the two meridional isomers showing photoluminescence quantum yields, ΦPL, in doped films of 80% and 89%. The two meridional isomers are used to assess the impact of emitters containing bulky, sterically demanding ligands on the performance of organic light‐emitting diodes (OLEDs). OLEDs employing a stepped doping profile with mer‐Ir(tfpi_tmBn)3 as the emitter produce the highest performing devices in this study, with these devices exhibiting deep‐blue [λEL = 429 nm, CIE = (0.16, 0.08)] emission and a maximum external quantum efficiency (EQEmax) of 14.9%, which decreases to 11.7% at 100 cd m−2. The performance of the OLEDs shows very good efficiencies and moderate efficiency roll‐offs in comparison to reported phosphorescent deep‐blue OLEDs with CIEy ≤ 0.08, as required for commercial displays. The promising results suggest that the design strategy of adding steric bulk to blue emitting iridium complexes containing NHC ligands is a useful strategy for reducing intermolecular interactions between emitters in OLEDs. [ABSTRACT FROM AUTHOR]

: Copyright of Advanced Optical Materials is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Wu, Sen, Kumar Gupta, Abhishek, Yoshida, Kou, Gong, Junyi, Hall, David, Cordes, David B., Slawin, Alexandra M. Z., Samuel, Ifor D. W., Zysman‐Colman, Eli

المصدر: Angewandte Chemie; 12/23/2022, Vol. 134 Issue 52, p1-9, 9p

مصطلحات موضوعية: DELAYED fluorescence, LIGHT emitting diodes, ORGANIC light emitting diodes, DIPOLE moments, QUANTUM efficiency

مستخلص: Herein, we demonstrate how judicious selection of the donor decorating a central multi‐resonant thermally activated delayed fluorescence (MR‐TADF) core based on DiKTa can lead to very high‐performance OLEDs. By decorating the DiKTa core with triphenylamine (TPA) and diphenylamine (DPA), 3TPA‐DiKTa and 3DPA‐DiKTa exhibit bright, narrowband green and red emission in doped films, respectively. The OLEDs based on these emitters showed record‐high performance for this family of emitters with maximum external quantum efficiencies (EQEmax) of 30.8 % for 3TPA‐DiKTa at λEL of 551 nm and 16.7 % for 3DPA‐DiKTa at λEL=613 nm. The efficiency roll‐off in the OLEDs was improved significantly by using 4CzIPN as an assistant dopant in hyperfluorescence (HF) devices. The outstanding device performance has been attributed to preferential horizontal orientation of the transition dipole moments of 3TPA‐DiKTa and 3DPA‐DiKTa. [ABSTRACT FROM AUTHOR]

: Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Wong, Michael Yin, Krotkus, Simonas, Copley, Graeme, Li, Wenbo, Murawski, Caroline, Hall, David, Hedley, Gordon, Jaricot, Marie, Cordes, David B., Slawin, Alexandra M. Z., Olivier, Yoann, Beljonne, David, Muccioli, Luca, Moral, Mónica, Sancho-García, Juan Carlos, Gather, Malte C, Samuel, Ifor D. W., Zysman-Colman, Eli

المساهمون: EPSRC, European Commission, University of St Andrews. School of Physics and Astronomy, University of St Andrews. School of Chemistry, University of St Andrews. EaSTCHEM, University of St Andrews. Biomedical Sciences Research Complex, University of St Andrews. Condensed Matter Physics

مصطلحات موضوعية: Thermally activated delayed fluorescence, Organic light emitting diodes, Oxadiazoles, Blue emitters, DFT calculations, QD Chemistry, DAS, QD

الوصف: EZ-C thanks the University of St Andrews for support. The authors are grateful to the EPSRC for financial support (grants EP/P010482/1, EP/J01771X and EP/J00916). IDWS is a Royal Society Wolfson Research Merit Award Holder. CM acknowledges funding by the European Commission through a Marie Skłodowska Curie Individual Fellowship (No. 703387). ; A series of four novel deep blue to sky blue thermally activated delayed fluorescence (TADF) emitters (2CzdOXDMe, 2CzdOXD4MeOPh, 2CzdOXDPh and 2CzdOXD4CF3Ph) have been synthesized and characterized. These oxadiazole-based emitters demonstrated bluer emission compared with reference emitter 2CzPN thanks to the weaker acceptor strength of oxadiazole moieties. In particular, the oxadiazole compounds doped in hosts (mCP and PPT) emitted from 435-474 nm with photoluminescence quantum yields ranging from 14%-55%. The emitters possess relatively large singlet-triplet excited state energy gaps (ΔEST) from 0.25-0.46 eV resulting in long lifetimes of the delayed components ranging from 4.8 to 25.8 ms. Electroluminescent devices using these oxadiazole emitters as dopant emitters gave emission maxima (λEL) from 446 nm to 474 nm with maximum external quantum efficiencies ranging from 4.2-11.2%. ; Peer reviewed

وصف الملف: application/pdf

العلاقة: ACS Applied Materials & Interfaces; 255931811; bfac0ac4-4564-4da8-9f94-e28077839dbb; 85053880505; 000446919800047; Wong , M Y , Krotkus , S , Copley , G , Li , W , Murawski , C , Hall , D , Hedley , G , Jaricot , M , Cordes , D B , Slawin , A M Z , Olivier , Y , Beljonne , D , Muccioli , L , Moral , M , Sancho-García , J C , Gather , M C , Samuel , I D W & Zysman-Colman , E 2018 , ' Deep blue oxadiazole-containing thermally activated delayed fluorescence emitters for organic light-emitting diodes ' , ACS Applied Materials & Interfaces , vol. In press . https://doi.org/10.1021/acsami.8b11136Test; RIS: urn:AF44D71EF8C93391DD08C7471B5D579E; ORCID: /0000-0002-5366-9168/work/48516818; ORCID: /0000-0002-4857-5562/work/48516878; ORCID: /0000-0001-7183-6022/work/56639105; ORCID: /0000-0002-9527-6418/work/56861814; https://hdl.handle.net/10023/18433Test; EP/P010482/1; EP/J01771X/1; 703387

الإتاحة: https://doi.org/10.1021/acsami.8b11136Test
https://hdl.handle.net/10023/18433Test

المؤلفون: Zhang, Zhen, Crovini, Ettore, dos Santos, Paloma L., Naqvi, Bilal A., Cordes, David B., Slawin, Alexandra M. Z., Sahay, Prakhar, Brütting, Wolfgang, Samuel, Ifor D. W., Bräse, Stefan, Zysman‐Colman, Eli

المصدر: Advanced Optical Materials; 12/3/2020, Vol. 8 Issue 23, p1-8, 8p

مصطلحات موضوعية: DELAYED fluorescence, BLUE light emitting diodes, ORGANIC light emitting diodes, QUANTUM efficiency

مستخلص: Organic thermally activated delayed fluorescent (TADF) materials can harvest 100% of the electrically generated excitons as a result of their small singlet–triplet energy difference. However, maximizing the external quantum efficiency (EQE) of a device also requires enhancing the light out‐coupling efficiency. This work presents a new acceptor–donor–acceptor (ADA) emitter employing an indolocarbazole donor and diphenyltriazine acceptors that show nearly‐completely horizontal orientation regardless of the host matrix, leading to a sky‐blue organic light‐emitting diode (λEL = 483 nm, CIE coordinates of 0.17, 0.32) with EQEMAX of 22.1%, a maximum luminance of 7800 cd m−2, and blue emission. [ABSTRACT FROM AUTHOR]

: Copyright of Advanced Optical Materials is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)