An excellent bipolar host material exhibiting EQE of 24.0% with small efficiency roll-off in solution-processable thermally activated delayed fluorescence OLEDs

Abstract

The D–A–D′-type novel organic material APC was designed and synthesized as a host for TADF emitters. APC realized an external quantum efficiency of 24.0% and also retained 23.1 and 21.7% at high brightness of 500 and 1000 cd m−2, respectively.

Exploring Efficient Dual-Phase Emissive Fluorophores with High Mobility by Integrating a Rigid Donor and Flexible Acceptor

“…Moreover, at a high luminance of 1000 cd m –2 , the CE and PE of B2 maintain a relatively high efficiency value of 9.84 cd A –1 and 8.48 lm W 1– , respectively, which is greatly desired for the application of OLEDs. Based on the EQ E max values of devices B1 and B2 with 3.60% and 4.84%, the carrier balance factor (γ) can be calculated to be 85% and ∼100% according to the formula γ = E Q E E U E × P L Q Y × η o u t , respectively, where EUE is the exciton utilization efficiency (presetting 25%) and η out is the light out-coupling efficiency (presetting 20%) . The doped devices B3 and B4 exhibit singlet EL peaks in the range of 453–464 nm, which demonstrates that the emission stems from the guest.…”

“…where EUE is the exciton utilization efficiency (presetting 25%) and η out is the light out-coupling efficiency (presetting 20%). 42 The doped devices B3 and B4 exhibit singlet EL peaks in the range of 453−464 nm, which demonstrates that the emission stems from the guest. To further validate the energy transfer from the host to the guest, we further tested the PL spectra of the compound-CBP-doped film (Figure S11).…”

Hydrophobic, Sustainable, High-Barrier Regenerated Cellulose Film via a Simple One-Step Silylation Reaction

“…Petroleum-derived synthetic polymers, such as polystyrene (PS), polyethylene (PE), and polyethylene terephthalate (PET), have been the main sources of various polymer films because they are easily processable, low-cost, durable, and highly scalable materials [1][2][3]. Polymer films have numerous industrial applications, including in the food packaging industry.…”

High-Performance, Solution-Processable Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes Realized via the Adjustment of the Composition of the Organoboron Acceptor Monomer in Copolymer Host Materials

“…However, compared to TADF emitters, host materials are seldom reported because of design difficulties due to the host materials having to satisfy the following criteria. ,− Host materials should have sufficiently high singlet and triplet energies for exciton confinement in emitters, appropriate highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, greater charge balance (i.e., bipolar nature) for facile charge injection and transportation, and a broad overlap of the host emission with the emitter absorption spectrum. Moreover, sufficient solubility in common organic solvents is expedient to the fabrication of solution-processable OLEDs, which are moderately easier to fabricate, cheaper, and applicable to large-area displays. − In particular, polymers, compared to their small-molecule counterparts, are more promising for manufacturing devices through the solution process because of their facile functionality to introduce various electron donors and acceptors and their capability of producing smooth and homogeneous films without any pinholes and phase separation during device fabrication. ,− However, because of difficulties in the design and synthesis of polymers that have high triplet energies, small molecules have been continuously developed and implemented as hosts for solution-processable TADF OLEDs. − Meanwhile, in the reviewed literature, few reports thus far have demonstrated the use of polymers as host materials. − …”