ABSTRACT
Photonic heterostructures with codable properties have shown great values as versatile information carriers at the micro and nanoscale. These heterostructures are typically prepared by a step-by-step growth or post-functionalization method to achieve varied emission colors among different building blocks. In order to realize high-throughput and multivariate information loading, we report here a strategy to integrate polarization signals into photonic heterojunctions. A U-shaped di-Pt(II) complex is assembled into highly-polarized yellow-phosphorescent crystalline microrods (Y-rod) by strong intermolecular Pt···Pt interaction. Upon end-initiated desorption of the incorporated CH2Cl2 solvents, Y-rod is transformed in a domino fashion into tri-block polarized photonic heterojunctions (PPHs) with alternate red-yellow-red emissions or red-phosphorescent microrods (R-rod). The red emissions of these structures are also highly polarized; however, their polarization directions are just orthogonal to those of the yellow phosphorescence of Y-rod. With the aid of a patterned mask, R-rod is further programmed into multi-block PPHs with precisely-controlled block sizes by side-allowed adsorption of CH2Cl2 vapor. X-ray diffraction analysis and theoretical calculations suggest that the solvent-regulated modulation of intramolecular and intermolecular excited states is critical for the construction of these PPHs.
ABSTRACT
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 560â 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 480â 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.