A novel nematic tri-carbazole as a hole-transport material for solution-processed OLEDs. Issue 1 (2nd January 2021)

• Record Type: Journal Article
• Authors: Hu, Guang; Kitney, Stuart P.; Billa, Muralidhar Reddy; Kelly, Stephen M.; Lambert, Brian; Harrison, William
• Is Part Of: Liquid crystals. Volume 48:Issue 1(2021)
• Page Start: 63
• Page End: 74
• Publication Date: 2021-01-02
• Subjects: Tri-carbazole liquid crystalline isomers -- nematic mesophases -- hole transport materials -- solution-processed OLED; Liquid crystals -- Periodicals; 548.905
• DOI: 10.1080/02678292.2020.1765262
• Languages: English
• ISSNs: 0267-8292

Abstract

ABSTRACT: Two structural isomers of alkyl-substituted tri-carbazoles were synthesised to study the effect of the substitution pattern on their liquid crystalline behaviour and conductivity and performance in test OLEDs. The isomer with a 2, 7-disubstitution pattern in the central carbazole exhibits a monotropic nematic phase, a high conductivity up to 10 Cd A −1 and is suitable as a hole-transport material for solution-processed OLEDs, achieving a high efficiency. The tri-carbazole isomer with a 3, 6-substitution pattern, in the central carbazole, does not exhibit observable liquid crystalline behaviour, exhibits conductivity values two orders of magnitude lower than that of its 2, 7-disubstituted isomer and performs poorly in OLEDs with the same configuration. GRAPHICAL ABSTRACT: Two structural isomers of alkyl-substituted tri-carbazoles A and B exhibit significantly different liquid crystalline behaviour, conductivity and performance in test OLEDs dependent upon their molecular shape. uf0001