High-performance solution-processed red hyperfluorescent OLEDs based on cibalackrot

Abstract

Hyperfluorescent organic light-emitting diodes (OLEDs) has allowed remarkable device performances to be achieved using fluorescent emitters. Superior device performance has been realised using thermally evaporated emissive layers. However, for future...

Cibalackrot Dendrimers for Hyperfluorescent Organic Light‐Emitting Diodes

“…[ 27,28 ] Herein, we only focused our studies on blend films, with the photophysical properties of the dendrimers investigated in a mixed host of 4CzIPN‐ t Bu:CBP (≈30:70 mol% blend ratio) (spin‐coated from chloroform solutions) for their application in HF‐OLEDs. [ 12 ] Where 4CzIPN‐ t Bu is 1,2,3,5‐tetrakis(3,6‐di‐ tert ‐butyl‐carbazol‐9‐yl)‐4,6‐dicyanobenzene and CBP is 4,4'‐bis( N ‐carbazolyl)‐1,1'‐biphenyl. As observed in Figure S10 (Supporting Information), the absorption of all blends is dominated by both CBP and 4CzIPN‐ t Bu hosts with little contribution from the dendrimers due to their relatively low blend ratios (0.5–1.5mol%).…”

“…Considering that the photophysical properties are comparable between blend ratios, these efficiency losses may be related to DET as short‐range interactions between 4CzIPN‐ t Bu → Cibalackrot improve, increasing competing DET losses compared with FRET. While these losses are clearly reduced in comparison with Cibalackrot B , [ 12 ] the Cibalackrot core is not fully protected by the two dendrons, as interaction can still occur facilely along the bay‐region of the molecule as observed in Figure 4. Thus, inefficient toward the prevention of DET to the fluorescent end‐emitting core.…”

“…[ 11 ] More recently, to suppress triplet transfer to a nondendritic end‐emitter, we demonstrated the use of a bulky TADF assistant host with a Cibalackrot derivative, Cibalackrot B , to achieve high‐performance red HF‐OLEDs. [ 12 ] However, the relatively flat and rigid structure of the Cibalackrot leads to severe solid‐state aggregates through π–π stacking. [ 13 ] This unfortunately results in poor solid‐state photoluminescence quantum efficiencies (PLQYs) even at low doping concentrations, in addition to its low solubility in organic solvents making film formation challenging.…”

Thermally Activated Delayed Fluorescence Sensitizers As Organic and Green Alternatives in Energy-Transfer Photocatalysis

“…Literature data were obtained via flashphotolysis (†) or transient absorption spectroscopy (‡), and unless otherwise stated, all other data are obtained by time-resolved photoluminescence spectroscopy. The references are included in brackets (refs , , , , − ).…”

Solution processable carbazole-benzophenone derivatives as bipolar hosts enabling high-efficiency stable green TADF organic LEDs

“…high singlet-triplet energies to confine exciton in the emissive layer, suitable molecular orbital energy levels to confine charge carriers into emitters, bipolar characteristics to facile charge injection and transportation in emissive layer, easy and solubility in common solvents. 29,30 Currently, solution processable TADF organic LEDs have been attracting attention for being cost-effective, possessing a simpler design structure, and capability of being scaled up for large area displays. 30 However, most of the materials with dry process compatibility are not compatible for solution process adoption due to poor solubility and crystallization of the film upon spin casting, thus there needs to be a further investigation in synthesis of compatible small molecules.…”