Alkylated indolo[3,2,1-jk]carbazoles as new building blocks for solution processable organic electronics

Efficient narrow green organic light-emitting diodes with low efficiency roll-offs based on iridium(iii) complexes containing indolo[3,2,1-jk]carbazole and pyrimidine units

“…10 Among the available rigid groups, indolo[3,2,1-jk]carbazole (ICz) stands out as a planar and rigid aromatic unit with excellent thermal and morphological stability, 11 high carrier-transport ability, 12 and high triplet excitation energy, 13 which has been widely used in a State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of materials for solar cells 14 and OLEDs. 15 In our previous work, we successfully incorporated the ICz unit into Ir(III) complexes for the first time, and the OLED based on a green emitter (pyidcz) 2 Ir(tmd) (pyidcz: 2-(pyridin-2-yl)indolo[3,2,1-jk]carbazole, tmd: 2,2,6,6-tetramethyl-3,5-heptanedione) exhibited a maximum external quantum efficiency (EQE max ) of 21.2%, and an electroluminescence (EL) spectrum peaking at 502 nm with a FWHM of 33 nm. 10 Similarly, the OLED based on an Ir(III) complex containing a pyrido[3 0 ,2 0 :4,5]pyrrolo[3,2,1-jk]carbazole unit showed an EQE max of 23.8%, and an EL spectrum peaking at 501 nm with a narrow FWHM as low as 30 nm and a maximum external quantum efficiency (EQE max ) of 23.8%.…”