Designing Hybrid Chiral Photonic Films with Circularly Polarized Room-Temperature Phosphorescence

Abstract

Circular polarized luminescence (CPL) is essential to chiral sciences and photonic technologies, but the achievement of circular polarized room-temperature phosphorescence (CPRTP) remains a great challenge due to the instability of triplet state excitons. Herein, we found that dual CPL and CPRTP were demonstrated by hybrid chiral photonic films designed by the coassembly of cellulose nanocrystals (CNCs), poly(vinyl alcohol) (PVA), and carbon dots (CDs). Tunable photonic band gaps were achieved by regulating the ratio of CNC/PVA in the hybrid films, leading to tunable CPL with invertible handedness, tunable wavelengths, and considerable dissymmetric factors (g lum ) up to −0.27. In particularly, triplet excitons produced by CDs were stable in the chiral photonic crystal environment, resulting in tunable right-handed CPRTP with long lifetimes up to 103 ms and large RTP dissymmetric factors (g RTP ) up to −0.47. Moreover, patterned films with multiple polarized features were demonstrated by a mold technique.

Bio‐Organic Chiral Nematic Materials with Adaptive Light Emission and On‐Demand Handedness

“…The asymmetric factor, | g lum | of 0.61, achieved here is much higher than those reported for chiral‐induced CPL emission with CNC materials. [ 25,27,50 ] The origin of active CPL emission in our work is distinguished with passive right‐handed CPL emission with negative g lum value induced by overlapping between photonic bandgap and emission band (Figure S20, Supporting Information). [ 22,24–26 ]…”

“…The asymmetric factor, |g lum | of 0.61, achieved here is much higher than those reported for chiral-induced CPL emission with CNC materials. [25,27,50] The origin of active CPL emission in our work is distinguished with passive right-handed CPL emission with negative g lum value induced by overlapping between photonic bandgap and emission band (Figure S20, Supporting Information). [22,[24][25][26] To further investigate dynamic control of the light emission, we triggered the reversible isomerization of SP molecules by changing the surrounding pH environment through exposure to acid and water vapor treatments in an alternating manner (Figure 5a, top).…”

“…Although few studies have been focused on enabling both CPL emissions with both handedness by controlling selective reflection with manipulation of helical pitch, the polarization quality of left-handed CPL emission resulting from chiral induced emissive dopants was not comparable with right-handed CPL emission and the mechanism for left-handed CPL emission remained unclear. [25,27] Furthermore, there have been no attempts to realize real-time switching ability of handedness in CPL emission. Clearly, the direct generation of CPL with dynamic switchable handedness will facilitate its application as advanced optical devices such as electro-tunable optical diodes.…”

3D Laser Displays Based on Circularly Polarized Lasing from Cholesteric Liquid Crystal Arrays

“…When a fluorescent dye is doped into the R‐CLCs, provided that the fluorescence of the dye overlaps with the PBG band, L‐CPL emission is achieved as a result of the forbidden nature of the R‐CPL emission within the PBG under certain pumping conditions (Figure S3). [ 35 ] Similarly, R‐CPL emission is obtained in left‐handed CLCs (L‐CLCs). The well‐assembled periodic helical superstructure of CLCs gives rise to a high degree of CPL emission at a given wavelength, which is favorable to the realization of compelling 3D displays.…”

Signal transmission encryption based on dye-doped chiral liquid crystals via tunable and efficient circularly polarized luminescence

“…By designing the types and proportions of chiral molecules, luminophores, and main liquid crystals of N*LC, the |g lum | of obtained CPL can reach the order from 10 -1 to 1. 11,[17][18][19][20][21][22][23][24][25] Moreover, it is a flexible design that the units in N*LC can be either doped independently or connected by the covalent bond. In addition, substantial effort has been devoted to introducing functional groups in N*LC units so that using multiple physical stimuli, like electric field [26][27][28][29][30] , light 29 and thermal 20,31 to tune CPL activity, can be realized.…”