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

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 54378 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.