Pyridinylphosphorothioate-Based Blue Iridium(Iii) Complex With Double Chiral Centers For Circularly Polarized Electroluminescence Dagger

Circularly polarized organic light-emitting diodes (CP-OLEDs) have received considerable attention due to their promising applications in 3D displays. However, up to now, CP-OLEDs using iridium(iii) phosphors as emissive dopants exhibited low brightness, insufficient efficiency, serious efficiency roll-off, and especially low electroluminescence dissymmetry factors (g(EL)). In this study, a blue Ir(iii) complex Ir(dfppy)(2)(sdpp) (dfppy is 2-(2,4-difluorophenyl)pyridine, sdpp is pyridinylphosphorothioate) peaking at 466 nm was synthesized, and two pairs of enantiomers containing the lambda or delta isomer together with a chiral phosphine center (R or S) were separated into lambda-Ir(dfppy)(2)(S-sdpp), delta-Ir(dfppy)(2)(R-sdpp), lambda-Ir(dfppy)(2)(R-sdpp) and delta-Ir(dfppy)(2)(S-sdpp), respectively. It is the first example to investigate phosphine chirality in an Ir(iii) complex, and the electron cloud distribution in the chiral conjugated ancillary ligand and lambda/delta chirality of the Ir(iii) center induced Ir(dfppy)(2)(sdpp) to exhibit decent circularly polarized luminescence (CPL) activities with a dissymmetry factor (|g(PL)|) around 1.4 x 10(-3). The OLEDs based on Ir(dfppy)(2)(sdpp) exhibited a maximum external quantum efficiency of 13.8% with mild efficiency roll-off. Notably, the CP-OLEDs based on lambda-Ir(dfppy)(2)(S-sdpp), delta-Ir(dfppy)(2)(R-sdpp), lambda-Ir(dfppy)(2)(R-sdpp) and delta-Ir(dfppy)(2)(S-sdpp) showed obvious circularly polarized electroluminescence (CPEL) signals with a g(EL) of -2.1 x 10(-3), 2.4 x 10(-3), -2.1 x 10(-3) and 1.9 x 10(-3), respectively, thus affording an efficient strategy for the design of chiral blue Ir(iii) emitters and their CP-OLEDs.