A Molecular Glass for Deep‐Blue Organic Light‐Emitting Diodes Comprising a 9,9′‐Spirobifluorene Core and Peripheral Carbazole Groups

Abstract

Novel fluorene‐based compounds, TCPC‐6 and TCPC‐4, with rigid central spirobifluorene cores and peripheral carbazole groups are synthesized using the Suzuki coupling reaction. The optical, electrochemical, and thermal properties of these compounds are characterized. The compounds show strong deep‐blue emission both in solution and as thin films. Both TCPC‐6 and TCPC‐4 exhibit amorphous morphologies in the solid state with high glass transition temperatures (Tg) of 108 and 143 °C, respectively. Atomic force microscopy (AFM) measurements indicate that high‐quality amorphous films of these novel compounds can be prepared by spin‐coating. The oxidation potentials of TCPC‐6 and TCPC‐4 are significant lower than that of model compounds without peripheral carbazole groups, which suggests that these compounds have relatively high highest occupied molecular orbital (HOMO) energy levels and better hole‐injection capabilities. Light‐emitting devices fabricated by spin‐coating films of these molecules exhibit deep‐blue emission with Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (x, y) of (0.16, 0.05); the devices fabricated using spin‐coated TCPC‐6 and TCPC‐4 layers exhibit high luminance efficiencies of 1.35 and 0.90 cd A–1 (with external quantum efficiencies of 3.72 and 2.47 %), respectively.

New Triazine-Based Polymers with Low Dielectric Constants and High Thermostability Derived from Biorenewable Anethole and Thermocrosslinkable Benzocyclobutene

“…As shown in Figure , monomer 5 displays a melting point (177.6 °C), whereas monomers 4 and 6 only exhibit T g s (see the inset in Figure ) at about 70 and 90 °C, respectively. The behaviors of monomers 4 and 6 are similar to that of the molecular glass previously reported. − The thermal polymerization of the three monomers occurs at above 200 °C, and the maximum exothermic peaks are observed at approximate 258 °C, similar to the curing reaction of the traditional benzocyclobutene-containing monomers. , …”

Blue-light-emitting and hole-transporting molecular materials based on amorphous triphenylamine-functionalized twisted binaphthyl

“…Device B1 with compound 5 as the emitter shows the maximum brightness of 3302 cd/m 2 at 11.5 V and the maximum current efficiency of 1.16 cd/A at 7.5 V. Similar results were obtained from device B2. These results are close to previously reported performances for OLEDs based on anthracene-containing binaphthol chromophores compounds (0.7-1.5 cd/A) [13b], dispiro-Xanthene-indenofluorene (1.0 cd/A) [17], fluorine-based compounds TCPC-6 (1.35 cd/A) [18]. However, they are lower than with the anthracene derivative with a tetraphenylethylene group (3.1 cd/A) [19], the pyrene-functionalized carbazole derivative (2.53 cd/A) [20] and device based on benzenelinked tetraphenylethene compounds (2.3-5.0 cd/A) [21].…”

Nondoped Deep‐Blue Organic Light‐Emitting Diodes with Color Stability and Very Low Efficiency Roll‐Off: Solution‐Processable Small‐Molecule Fluorophores by Phosphine Oxide Linkage

“…The best EL performance is achieved by PO4 with a maximum current efficiency η c,max of 2.36 cd A −1 , a maximum power efficiency η p,max of 1.86 Lm W −1 , and a maximum external quantum efficiency η ext,max of 2.06 %, which is comparable with the best device performances in the literature for solution‐processed small‐molecular nondoped deep‐blue OLEDs 26–27. 30, 32–37 For example, Ma et al.…”