Substituent effects of iridium (III) complexes with 2,4-diphenylquinoline for efficient red organic light-emitting diodes

Abstract

We demonstrate efficient red electrophosphorescence using bis[2-(5-methoxyphenyl)-4-phenylquinolinato- N,C 2] iridium(III)(acetylacetonate) [Ir(dpq-5OCH 3) 2(acac)], bis[2-(5-methylphenyl)-4-phenylquinolinato- N,C 2] iridium(III)(acetylacetonate)[Ir(dpq-5CH 3) 2(acac)] and bis[2-(5-fluorophenyl)-4-phenylquinolinato- N,C 2] iridium(III) (acetylacetonate) [Ir(dpq-5F) 2(acac)] in compared with bis[2,4-diphenylquinolinato- N,C 2] iridium(III)(acetylacetonate) [Ir(dpq) 2(acac)]. The –CH 3, –OCH 3 and –F group substituted on the 5′-position of phenyl ring strongly affected the energy level of molecule. The organic light-emitting diodes (OLEDs) with Ir(dpq-5OCH 3) 2(acac), Ir(dpq-5CH 3) 2(acac), Ir(dpq-5F) 2(acac) and Ir(dpq) 2(acac) have a maximum luminous efficiency of 8.20 cd/A, 10.20 cd/A, 15.80 cd/A and 11.60 cd/A, respectively. Also, their electroluminescent emission appeared at 605, 617, 610 and 617 nm, respectively.