Thermally activated delayed fluorescence emitters showing wide-range near-infrared piezochromism and their use in deep-red OLEDs
Abstract
Organic small molecules exhibiting both thermally activated delayed fluorescence (TADF) and wide-ranging piezochromism (Δλ > 150 nm) in the near-infrared region have rarely been reported in the literature. We present three emitters MeTPA-BQ, tBuTPA-BQ and TPPA-BQ based on a hybrid acceptor, benzo[g]quinoxaline-5,10-dione, that emit via TADF, having photoluminescence quantum yields, ΦPL, of 39–42% at photoluminescence (PL) maxima, λPL, of 625–670 nm in 2 wt% doped films in 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP). Despite their similar chemical structures, the PL properties in the crystalline states of MeTPA-BQ (λem = 735 nm, ΦPL = 2%) and tBuTPA-BQ (λem = 657 nm, ΦPL = 11%) are significantly different. Further, compounds tBuTPA-BQ and TPPA-BQ showed a significant PL shift of ∼98 and ∼165 nm upon grinding of the crystalline samples, respectively. Deep-red organic light-emitting diodes with MeTPA-BQ and tBuTPA-BQ were also fabricated, which showed maximum external quantum efficiencies, EQEmax, of 10.1% (λEL = 650 nm) and 8.5% (λEL = 670 nm), respectively.
Citation
Sudhakar , P , Gupta , A K , Cordes , D B & Zysman-Colman , E 2023 , ' Thermally activated delayed fluorescence emitters showing wide-range near-infrared piezochromism and their use in deep-red OLEDs ' , Chemical Science , vol. Advance article . https://doi.org/10.1039/D3SC05188A
Publication
Chemical Science
Status
Peer reviewed
ISSN
2041-6520Type
Journal article
Description
This project is funded by European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreements No. 891606 (TADFNIR). We thank the Engineering and Physical Sciences Research Council for funding. (EP/R035164/1).Collections
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