In:
Materials Horizons, Royal Society of Chemistry (RSC), Vol. 9, No. 2 ( 2022), p. 772-779
Abstract:
Near-infrared thermally activated delayed fluorescence (NIR-TADF) materials with emission over 700 nm have been insufficiently investigated mainly due to the limited choice of strong donor/acceptor units for molecular construction and the limited electronic coupling between the donors and acceptors. Herein, a novel D–A1–A2–A3 configuration was developed for the design of a NIR-TADF material (TPA-CN-N4-2PY), in which three types of sub-acceptor units (CN: cyano; N4: dipyrido[3,2- a :2′,3′- c ]phenazine; PY: pyridine) were incorporated into a molecular skeleton to reinforce the electron-accepting strength. The attachment of two pyridine units on TPA-CN-N4 produced TPA-CN-N4-2PY with an extended π-backbone, which shifted the electroluminescence (EL) emission into the NIR region and enhanced the horizontal ratio of emitting dipole orientation ( Θ // ) simultaneously. TPA-CN-N4-2PY-based OLEDs demonstrated a record-high external quantum efficiency (EQE) of 21.9% with an emission peak at 712 nm and Θ // = 85% at the doping ratio of 9.0 wt%. On the contrary, the parent compound TPA-CN-N4-based OLEDs at the same doping ratio achieved an EQE of 23.4% at 678 nm with Θ // = 75%. This multiple sub-acceptors approach could enrich the design strategy of the NIR-TADF materials, and the large conjugated system could improve the Θ // for achieving efficient emitters.
Type of Medium:
Online Resource
ISSN:
2051-6347
,
2051-6355
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2744250-0