Assembling semiconductor quantum dots in hierarchical photonic cellulose nanocrystal films: circularly polarized luminescent nanomaterials as optical coding labels

Exploring semiconductor quantum dots (QDs) with circularly polarized luminescence (CPL) is desirable to design optoelectronic devices owing to the easily tunable emission wavelengths and photophysical stability. In this study, through a co-assembly strategy, semiconductor QDs were encapsulated in cellulose nanocrystal (CNC)-based left-handed hierarchical photonic films, which resulted in circularly polarized luminescent nanomaterials with right-handed polarization, full-color tunable wavelengths, and tailored dissymmetry factors (g(lum)). The CPL wavelength was manipulated by the emission wavelength of the semiconductor QDs. The photonic band gaps (PBGs) and handedness that spanned the visible spectrum were controlled by the glycerol content in the co-assembled photonic films. This enabled tunable CPL from the green-emitting QDs with a tailored maximum g(lum) from -0.48 to -0.21, which is considerable for semiconductor nanomaterials. Based on the circularly polarized information in the ground state and excited state, CPL photonic films were developed as optical labels to encode and decode information.