In:
Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 10, No. 2 ( 2022), p. 768-773
Abstract:
Highly efficient multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters with narrowband emissions based on a boron/nitrogen (B/N) framework are crucial for next-generation full-color displays with high color purity. In this work, we develop a simple molecular design strategy for MR-TADF materials based on a skeleton of phenoxazine units and amplification at the para -position of the boron atom by different electron-donating groups (phenoxazine/ tert -butylcarbazole). Two novel phenoxazine-fused MR-TADF materials, TPXZBN and DPXZCZBN, show green emissions with sharp peaks at 502 nm and 500 nm, with small full-width at half maximum (FWHM) bandwidths of 33 nm and 32 nm, respectively. TPXZBN and DPXZCZBN also exhibit small singlet–triplet state energy gaps (Δ E st s) of 0.16 eV and 0.13 eV, with high photoluminescence quantum yields (PLQYs) of 91% and 90% in toluene solutions, and 99% and 94% in doped films, respectively. The corresponding organic light-emitting diodes (OLEDs) based on TPXZBN and DPXZCZBN exhibited maximum external quantum efficiencies (EQE max s) of 21.3% and 19.8%, respectively, accompanied by small efficiency roll-offs, with EQEs of 17.2% and 18.8% at 100 cd m −2 , and 17.4% and 19.6% at 1000 cd m −2 , respectively. Notably, the small electroluminescence FWHMs of the OLEDs still remained at 37 nm and 36 nm, respectively.
Type of Medium:
Online Resource
ISSN:
2050-7526
,
2050-7534
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2702245-6
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