Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

Merve Karaman; Abhishek Kumar Gupta; Subeesh Madayanad Suresh; Tomas Matulaitis; Lorenzo Mardegan; Daniel Tordera; Henk J Bolink; Sen Wu; Stuart Warriner; Ifor D Samuel; Eli Zysman-Colman

doi:10.3762/bjoc.18.136

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

Beilstein J Org Chem. 2022 Sep 22:18:1311-1321. doi: 10.3762/bjoc.18.136. eCollection 2022.

Authors

Affiliations

¹ Department of Material Science and Engineering, Faculty of Engineering and Architecture, Izmir Katip, Celebi University, Cigli, 35620-Izmir, Turkey.
² Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST.
³ Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK.
⁴ Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna (Valencia), Spain.
⁵ School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK.

Abstract

We designed and synthesized two new ionic thermally activated delayed fluorescent (TADF) emitters that are charged analogues of a known multiresonant TADF (MR-TADF) compound, DiKTa. The emission of the charged derivatives is red-shifted compared to the parent compound. For instance, DiKTa-OBuIm emits in the green (λ_PL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λ_PL = 577 nm, 1 wt % in mCP). In 1 wt % mCP films, both emitters showed good photoluminescence quantum yields of 71% and 61%, and delayed lifetimes of 316.6 μs and 241.7 μs, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm, leading to reverse intersystem crossing rates of 2.85 × 10³ s^-1 and 3.04 × 10³ s^-1. Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λ_max = 534 nm) and red (λ_max = 656 nm) emission, respectively.

Keywords: electroluminescence; light-emitting electrochemical cells; multiresonance; purely organic emitters; thermally activated delayed fluorescence.

Grants and funding

M. K. would like to thank 2214-A International Research Fellowship Programme for Ph.D. students (1059B141900585). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No 838885 (NarrowbandSSL). S.M.S. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship (grant agreement No 838885 NarrowbandSSL). A. K. G. is grateful to the Royal Society for Newton International Fellowship NF171163. L.M acknowledges that the project who gave rise to these results received support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme Grant agreement No. 834431, the Spanish Ministry of Science, Innovation and Universities (MICIU, RTI2018-095362-A-I00, and EQC2018-004888-P) and the Comunitat Valenciana (IDIFEDER/2020/063 and PROMETEU/2020/077). D.T. acknowledges support from the Comunitat Valenciana (CIGE/2021/0).