Boost the Circularly Polarized Phosphorescence of Chiral Organometallic Platinum Complexes by Hierarchical Assembly into Fibrillar Networks

Circularly polarized luminescence (CPL)-active molecular materials have drawn increasing attention due to their promising applications for next-generation display and optoelectronic technologies. Currently, it is challenging to obtain CPL materials with both large luminescence dissymmetry factor (glum) and high quantum yield (Φ). A pair of enantiomeric N^N^C-type Pt(II) complexes (L/D)-1 modified with chiral Leucine methyl ester are presented herein. Though the solutions of these complexes are CPL-inactive, the spin-coated thin films of (L/D)-1 exhibit giantly-amplified circularly polarized phosphorescences with |glum| of 0.53 at 560 nm and Φair of ~50%, as well as appealing circular dichroism (CD) signals with the maximum absorption dissymmetry factor |gabs| of 0.37-0.43 at 480 nm. This superior CPL performance benefits from the hierarchical formation of crystalline fibrillar networks upon spin coating. Comparative studies of another pair of chiral Pt(II) complexes (L/D)-2 with a symmetric N^C^N coordination mode suggest that the asymmetric N^N^C coordination of (L/D)-1 are favorable for the efficient exciton delocalization to amplify the CPL performance. Optical applications of the thin films of (L/D)-1 in CPL-contrast imaging and inducing CP light generation from achiral emitters and common light-emitting diode lamps have been successfully realized.