Switchable circular polarized phosphorescence enabled by cholesteric assembled nanocelluloses

Circularly polarized room temperature phosphorescence (CP-RTP) has recently attracted great attention and is rapidly developing. To boost its potential applications in imaging, information encryption and optical detectors, high glum-factor and programmable chiroptical performance are needed. Herein, CP-RTP active materials were successfully constructed by infiltrating polycyclic aromatic hydrocarbon (naphthalene and pyrene) doped polymethyl methacrylate in cellulose nanocrystals (CNCs) films. It enabled a tunable glum-factor of up to -0.49 and an afterglow time of up to 8 s. Modulation of the matching degree of the photonic bandgap of CNCs films with the phosphor emission spectra allowed for achieving on-demand intensity, wavelength and handedness of CP-RTP and circularly polarized fluorescent (CP-FL) emission. Furthermore, dynamic tuning of the CP-RTP and CP-FL, including on/off, and positive/negative signal switching, was achieved through oxygen consumption by UV irradiation to reduce the effect of triplet oxygen quenching. The hybrid CNCs film demonstrated structural color, phosphorescence, and CP-RTP response, making it suitable for multiple channel information storage for anticounterfeiting as a porotype. These findings show a range of prospective photonic applications, including information security, stereoscopic displays, and chiral polarizers.