Development of Red Exciplex for Efficient OLEDs by Employing a Phosphor as a Component

Abstract

Exciplexes are ideal candidates as effective thermally activated delayed fluorescence (TADF) emitters. However, efficient orange and red TADF exciplexes have been reported seldomly, because their significant non-radiative (NR) decay of excited states lead to unavoidable energy loss. Herein, we propose a novel strategy to construct efficient red TADF exciplexes by introducing phosphor as one component. Due to the strong spin–orbit coupling of heavy metal (e.g., Ir, Pt, et al.) ion cores, the NR decays will be evidently decreased for both singlet and triplet excitons, reducing the undesired exciton waste. Moreover, compared with the conventional exciplexes, phosphorescence plays an important role for such novel exciplexes, further improving the exciton utilization. Based on this strategy, we fabricated a red exciplex containing 1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl)tris(diphenylphosphine oxide) (PO-T2T) and tris(2-phenylpyridine) iridium(III) (Ir(ppy)3) as components and realize a red emission with a peak at 604 nm, a CIE coordinate of (0.55, 0.44), and a high maximum external quantum efficiency of 5% in organic light-emitting device. This efficiency is 2.6 times higher than that of the device based on the conventional red exciplex emitter, proving the superiority of our novel strategy to construct TADF exciplexes with phosphors.

Exploring the Scope of Through-Space Charge-Transfer Thermally Activated Delayed Fluorescence in Acrylic Donor–Acceptor Copolymers

“…This avoids the strong electronic coupling observed in fully conjugated D–A polymers, favorable for achieving both blue emission and a small Δ E ST . − The same phenomenon can also be observed when donor and acceptor homopolymers are physically blended in a thin film . Using a TSCT approach, OLEDs have now been prepared with efficient white light emission as well as with colors spanning the visible spectrum from deep blue to red. ,,− …”

Hyaluronic Acid-Based Gold Nanoparticles for the Topical Delivery of Therapeutics to the Retina and the Retinal Pigment Epithelium

“…Although any drug-nanoparticle conjugates can be coated with HA, here we provide proof of concept using gold nanoparticles (AuNPs) because their size, shape, and surface properties can be precisely altered. Their unique surface plasmon resonance (SPR) effect can also be used for imaging [ 24 ], photothermal therapy [ 25 ], and anti-angiogenic therapeutic applications [ 26 ]. During choroidal neovascularization (CNV), endothelial cells over-express CD44 and vascular endothelial growth factor (VEGF), and therefore, the innate anti-angiogenic activity of AuNPs can be tested [ 27 ].…”

Novel donor-spacer-acceptor compound as the multifunctional component of exciplexes for efficient organic light-emitting diodes

“…Among the six exciplex emitters, m-MTDATA:3Cz-o-TRz exhibited the lowest efficiencies in the device. This result can be ascribed to the fact that the narrow bandgap of orange-red exciplex emitter greatly increases the non-radiative decays of excited states [35]. By contrast, the green OLEDs with TAPC:3Cz-o-TRz and 3Cz-o-TRz:PO-T2T as emitters achieved maximum CEs and EQEs of 39.3 and 37.2 cd A −1 and 12.1% and 11.8%, respectively, and remained at high values of 11.5% and 11.0% at a luminance of 1000 cd m −2 .…”