Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

Marc K. Etherington; Nadzeya A. Kukhta; Heather F. Higginbotham; Andrew Danos; Aisha N. Bismillah; David R. Graves; Paul R. McGonigal; Nils Haase; Antonia Morherr; Andrei S. Batsanov; Christof Pflumm; Vandana Bhalla; Martin R. Bryce; Andrew P. Monkman

doi:10.1021/acs.jpcc.9b01458

Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

Marc K. Etherington^*, Nadzeya A. Kukhta, Heather F. Higginbotham, Andrew Danos, Aisha N. Bismillah, David R. Graves, Paul R. McGonigal, Nils Haase, Antonia Morherr, Andrei S. Batsanov, Christof Pflumm, Vandana Bhalla, Martin R. Bryce, Andrew P. Monkman

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method, and its enduring presence contributes to the widely reported concentration-mediated red shift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.

Original language	English
Pages (from-to)	11109-11117
Number of pages	9
Journal	Journal of Physical Chemistry C
Volume	123
Issue number	17
DOIs	https://doi.org/10.1021/acs.jpcc.9b01458
Publication status	Published - 2 May 2019

Bibliographical note

Funding Information:
We thank W. D. Carswell for obtaining DSC and TGA data, Gary Oswald for collecting the powder X-ray diffraction patterns, and Dr D. S. Yufit for help with the single crystal X-ray study. The Diamond Light Source (RAL) is thanked for the award of instrument time on Station I19 (MT 11145) and the instrument scientists for their kind support. Funding: M.K.E., H.F.H., and A.P.M. acknowledge the EU’s Horizon 2020 research and innovation programme for funding the PHEBE project under Grant No. 641725. M.K.E., A.D., N.H., C.P., A.M., M.R.B., and A.P.M. also acknowledge the EU’s Horizon 2020 research and innovation programme for funding the HyperOLED project under grant agreement No. 732013. A.P.M. and M.R.B. also acknowledge the EPSRC for funding under grant number EP/L02621X/1. A.N.B. is supported by an EPSRC doctoral training grant. P.R.M. and A.P.M. thank BEIS and UUKi for support through a Rutherford Strategic Partner Grant. D.R.G. thanks Merck KGaA for funding his PhD studies.

Publisher Copyright:
© 2019 American Chemical Society.

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10.1021/acs.jpcc.9b01458

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Etherington, M. K., Kukhta, N. A., Higginbotham, H. F., Danos, A., Bismillah, A. N., Graves, D. R., McGonigal, P. R., Haase, N., Morherr, A., Batsanov, A. S., Pflumm, C., Bhalla, V., Bryce, M. R., & Monkman, A. P. (2019). Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials. Journal of Physical Chemistry C, 123(17), 11109-11117. https://doi.org/10.1021/acs.jpcc.9b01458

@article{b8aac597c68447d4bdd5fded964aa281,

title = "Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials",

abstract = "We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method, and its enduring presence contributes to the widely reported concentration-mediated red shift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.",

author = "Etherington, {Marc K.} and Kukhta, {Nadzeya A.} and Higginbotham, {Heather F.} and Andrew Danos and Bismillah, {Aisha N.} and Graves, {David R.} and McGonigal, {Paul R.} and Nils Haase and Antonia Morherr and Batsanov, {Andrei S.} and Christof Pflumm and Vandana Bhalla and Bryce, {Martin R.} and Monkman, {Andrew P.}",

note = "Funding Information: We thank W. D. Carswell for obtaining DSC and TGA data, Gary Oswald for collecting the powder X-ray diffraction patterns, and Dr D. S. Yufit for help with the single crystal X-ray study. The Diamond Light Source (RAL) is thanked for the award of instrument time on Station I19 (MT 11145) and the instrument scientists for their kind support. Funding: M.K.E., H.F.H., and A.P.M. acknowledge the EU{\textquoteright}s Horizon 2020 research and innovation programme for funding the PHEBE project under Grant No. 641725. M.K.E., A.D., N.H., C.P., A.M., M.R.B., and A.P.M. also acknowledge the EU{\textquoteright}s Horizon 2020 research and innovation programme for funding the HyperOLED project under grant agreement No. 732013. A.P.M. and M.R.B. also acknowledge the EPSRC for funding under grant number EP/L02621X/1. A.N.B. is supported by an EPSRC doctoral training grant. P.R.M. and A.P.M. thank BEIS and UUKi for support through a Rutherford Strategic Partner Grant. D.R.G. thanks Merck KGaA for funding his PhD studies. Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

year = "2019",

month = may,

day = "2",

doi = "10.1021/acs.jpcc.9b01458",

language = "English",

volume = "123",

pages = "11109--11117",

journal = "Journal of Physical Chemistry C",

issn = "1932-7447",

publisher = "American Chemical Society",

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Etherington, MK, Kukhta, NA, Higginbotham, HF, Danos, A, Bismillah, AN, Graves, DR, McGonigal, PR, Haase, N, Morherr, A, Batsanov, AS, Pflumm, C, Bhalla, V, Bryce, MR & Monkman, AP 2019, 'Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials', Journal of Physical Chemistry C, vol. 123, no. 17, pp. 11109-11117. https://doi.org/10.1021/acs.jpcc.9b01458

TY - JOUR

T1 - Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

AU - Etherington, Marc K.

AU - Kukhta, Nadzeya A.

AU - Higginbotham, Heather F.

AU - Danos, Andrew

AU - Bismillah, Aisha N.

AU - Graves, David R.

AU - McGonigal, Paul R.

AU - Haase, Nils

AU - Morherr, Antonia

AU - Batsanov, Andrei S.

AU - Pflumm, Christof

AU - Bhalla, Vandana

AU - Bryce, Martin R.

AU - Monkman, Andrew P.

N1 - Funding Information: We thank W. D. Carswell for obtaining DSC and TGA data, Gary Oswald for collecting the powder X-ray diffraction patterns, and Dr D. S. Yufit for help with the single crystal X-ray study. The Diamond Light Source (RAL) is thanked for the award of instrument time on Station I19 (MT 11145) and the instrument scientists for their kind support. Funding: M.K.E., H.F.H., and A.P.M. acknowledge the EU’s Horizon 2020 research and innovation programme for funding the PHEBE project under Grant No. 641725. M.K.E., A.D., N.H., C.P., A.M., M.R.B., and A.P.M. also acknowledge the EU’s Horizon 2020 research and innovation programme for funding the HyperOLED project under grant agreement No. 732013. A.P.M. and M.R.B. also acknowledge the EPSRC for funding under grant number EP/L02621X/1. A.N.B. is supported by an EPSRC doctoral training grant. P.R.M. and A.P.M. thank BEIS and UUKi for support through a Rutherford Strategic Partner Grant. D.R.G. thanks Merck KGaA for funding his PhD studies. Publisher Copyright: © 2019 American Chemical Society.

PY - 2019/5/2

Y1 - 2019/5/2

N2 - We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method, and its enduring presence contributes to the widely reported concentration-mediated red shift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.

AB - We expose significant changes in the emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise from the presence of persistent dimer states in thin films and organic light-emitting diodes (OLEDs). Direct photoexcitation of this dimer state in 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) reveals the significant influence of dimer species on the color purity of its photoluminescence and electroluminescence. The dimer species is sensitive to the sample preparation method, and its enduring presence contributes to the widely reported concentration-mediated red shift in the photoluminescence and electroluminescence of evaporated thin films. This discovery has implications on the usability of these, and similar, molecules for OLEDs and explains disparate electroluminescence spectra presented in the literature for these compounds. The dimerization-controlled changes observed in the TADF process and photoluminescence efficiency mean that careful consideration of dimer states is imperative in the design of future TADF emitters and the interpretation of previously reported studies of carbazole-based TADF materials.

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U2 - 10.1021/acs.jpcc.9b01458

DO - 10.1021/acs.jpcc.9b01458

M3 - Article

AN - SCOPUS:85065312903

SN - 1932-7447

VL - 123

SP - 11109

EP - 11117

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 17

ER -

Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials

Abstract

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