A universal thermally activated delayed fluorescent host with short triplet lifetime for highly efficient phosphorescent OLEDs with extremely low efficiency roll-off

Abstract

Triplet-involved quenching processes lead to significant efficiency roll-off in phosphorescent organic light-emitting diodes (OLEDs). Thermally activated delayed fluorescence (TADF) materials can reduce the triplet exciton density in the emitting layer...

Donor–Acceptor Type of Fused-Ring Thermally Activated Delayed Fluorescence Compounds Constructed through an Oxygen-Containing Six-Membered Ring

“…5–7.5%) of the OLEDs based on traditional fluorophores, , confirming the contribution of TADF to electroluminescence. The 5 wt % doped device of t-BMA­(OO)­Q showed weaker EQE roll-offs at higher luminance compared with the corresponding device of PA­(OO)­Q (Figure ), which is rational considering the shorter τ DF of the doped emitting layer of the t-BMA­(OO)­Q device. , Compared with the devices of PA­(O)­Q fabricated using the 5 wt % doping concentration (EQE max : 3.1%, FWHM: 81 nm/0.43 eV) and other doping concentrations, the 5 wt % doped device of PA­(OO)­Q has a much higher EQE max and a narrower electroluminescence bandwidth (FWHM: 73 nm/0.36 eV). Such advantages are greatly owing to the relatively higher Φ PL and narrower emission bandwidth of PA­(OO)­Q caused by the fused-ring core skeleton.…”

Highly efficient (EQE > 27%) Yellow OLEDs using spiro[fluorene-9,9′-phenanthren-10′-one]-carbazole-based donor–acceptor–donor host materials

“…It is worth noting that device BY4 with the MS-OC /CN-T2T mixed host exhibited a high maximum luminance, one of the highest values reported in the literature for PO-01-based devices. 34–37 On the other hand, in contrast to device BY1 , which exhibited a high turn-on voltage of 2.9 V (defined at the luminance of 1 cd m −2 ), devices BY2 , BY3 , and BY4 exhibited extremely low turn-on voltages of approximately 2.0–2.1 V. On comparing device BY4 with the previously reported PO-01-based devices (Table S5, ESI†) in terms of the device performance and luminance, the MS-OC /CN-T2T mixed host presented an outstanding balance in terms of the carrier mobility, yielding excellent performance, with high power efficiency, high maximum luminance, and low V on .…”

Using azaacene as an acceptor unit to construct an ultraefficient red fluorophore with an EQE over 40%

“…16 In hexane besides the structureless CT emission at 561 nm, AZA-TPA displayed a sharp local excited (LE) state emission at 531 nm because the CT state was destabilized in the non-polar solvent. 17…”