Diphenylsulfone-based hosts for electroluminescent devices: Effect of donor substituents

• Published in: Dyes and pigments 2020-04, Vol.175, p.108104, Article 108104
• Main Authors: Bezvikonnyi, Oleksandr, Gudeika, Dalius, Volyniuk, Dmytro, Rutkis, Martins, Grazulevicius, Juozas V.
• Format: Article
• Language: English
• Subjects: Carbazole; Diphenylsulfone; Host; OLED; TADF
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2019.108104

In this work, we report on a series of diphenylsulfone derivatives substituted by 2-(trifluoromethyl)-phenothiazinyl, 10,11-dihydro-5H-dibenz[b,f]azepinyl, 5H-dibenz[b,f]azepinyl, 4-methoxy-carbazolyl and 1,2,3,4-tetrahydrocarbazolyl moieties. Utilization of such donating units provided high triplet levels (2.99–3.12 eV) of the designed compounds. The compounds were characterized by glass-forming properties (with glass transition temperatures of 68–162 °C) and ionization potentials of 5.61–5.99 eV. Depending on the donor substitution pattern, either hole or electron transport was observed for the studied compounds with charge mobilities in the range from 5.3 × 10−6 to 2.8 × 10−4 cm2/V at electric fields higher than 3.1·105 V/cm. Hosting properties of the compounds were studied using widely known emitter exhibiting thermally activated delayed fluorescence. Among the studied compounds, bis(4-(4-methoxy-9H-carbazole-9-yl)phenyl)sulfone showed the best performances in both guest:host solid films (photoluminescence quantum yield of 87%) and electroluminescent devices (maximum external quantum efficiency over 20%). [Display omitted] •D-A-D type diphenylsulfone derivatives were synthesized.•All compounds formed glasses with glass transition temperatures ranging from 68 to 162 °C.•All hosts demonstrated high triplet energy levels of 2.99–3.08 eV.•Hole-transporting properties with charge mobility exceeding 10−4 cm2/V were estimated by time of flight technique.•Bluish-green TADF OLEDs with EQE of 20% were fabricated.