High performance solution-processed organic yellow light-emitting devices and fluoride ion sensors based on a versatile phosphorescent Ir(iii) complex

Abstract

An efficient phosphorescent iridium(III) complex (BPyPmIr) has been prepared with the asymmetric structure of (C^N1)(C^N2)Ir(acac) in which C^N1 and C^N2 are 5-(dimesitylboranyl)-2-phenylpyridine and 2-(2,4-difluorophenyl)pyrimidine, respectively, and acac is acetylacetonate. At room temperature, BPyPmIr shows a very high photoluminescence quantum yield (PLQY) of 0.88 in THF and nearly unity in doped films. A solution-processed yellow OLED based on BPyPmIr gives the maximum luminance (L_max), external quantum yield (EQE), current efficiency (CE), and power efficiency (PE) of 54 378 cd m⁻², 18.7%, 62.8 cd A⁻¹, and 60.9 lm W⁻¹, respectively, with very low efficiency roll-off at a high luminance of 1000 cd m⁻², which are among the highest efficiencies ever reported for solution-processed yellow OLEDs. Furthermore, because of the strong boron–fluoride ion interactions between the dimesitylboryl moiety and F⁻ ions, this Ir(III) complex can be used as an efficient “color-switch” sensor for detecting F⁻ ions. Besides its high sensitivity and selectivity, the detection limit of this Ir(III) complex is as low as 1.55 × 10⁻⁷ M.