High-efficiency and low roll-off deep-blue OLEDs enabled by thermally activated delayed fluorescence emitter with preferred horizontal dipole orientation
Journal
Chemical Engineering Journal
Journal Volume
433
Date Issued
2022
Author(s)
Abstract
Highly efficient blue thermally activated delayed fluorescence (TADF) materials with high horizontal dipole orientation (Θ//) remain a big challenge due to the concentration quenching effects and serious efficiency roll-offs in their corresponding organic light-emitting diodes (OLEDs). We herein report two novel TADF compounds, namely 2TDBA-SBA and TDBA-SBA, which were facilely synthesized by utilizing a rigid oxygen-bridged cyclized triarylboron-based unit (TDBA) as the acceptor and a spiro acridine (SBA) as the donor. Benefiting from the rigid and planar skeleton of the acceptor and the linear molecular shape, high Θ//s and photoluminescence quantum yields (PLQYs) of ? 90% were achieved. Significantly, TDBA-SBA exhibited excellent TADF properties with a short delayed fluorescence lifetime of only 684 ns and narrow full-width at half-maximum (FWHM) of 44 nm in solution state, accompanied by the high PLQYs of over 80% at high doping concentrations, manifesting the alleviated exciton quenching effects. Consequently, OLEDs based on TDBA-SBA achieved a high maximum external quantum efficiency (EQE) of 29.3% and a maximum brightness of 27663 cd cm?2. Importantly, an EQE over 20% was realized even at the high brightness of 10000 cd cm?2, signifying a small efficiency roll-off. ? 2021 Elsevier B.V.
Subjects
Efficiency roll-off
Horizontal dipole orientation
Organic light-emitting diodes
Reverse intersystem crossing
Thermally activated delayed fluorescence
Fluorescence
Luminance
Organic light emitting diodes (OLED)
Quantum efficiency
Quenching
Supercomputers
Dipole orientation
External quantum efficiency
Higher efficiency
Horizontal dipoles
Intersystem crossing
Photoluminescence quantum yields
Thermally activated delayed fluorescences
Efficiency
Type
journal article