[PtII(salophen)] complexes as aligned OLED emissive layer: a combination of molecular design, liquid crystal behavior and phosphorescent properties

Currently, OLED device efficiency is limited by light-trapping effects, which may be mitigated by inducing anisotropic emission. Platinum(II) complexes are promising phosphorescent emitters whose structures are compatible with liquid-crystalline materials, enabling self-assembly and potentially induce anisotropic emission. Herein, liquid-crystalline behavior was introduced into [PtII(salophen)] by varying the number and position of n-dodecyloxy substituents. Seven new complexes were synthesized. PtS{3/4,5} exhibited a stable hexagonal columnar mesophase with a phase transition near room temperature. All complexes showed orange-red emission in degassed solution and thin films, with photophysical properties depending on the substitution pattern. OLEDs based on PtS{0/4}, PtS{3/0}, and PtS{3/4} were fabricated. PtS{0/4} showed the best performance, whereas PtS{3/0} and PtS{3/4} exhibited similar behavior. Electroluminescence and anisotropic emission studies are ongoing.