Metal‐Enhanced Circularly Polarized Luminescence of Self‐Assembled Au@SiO₂ Triangular Nanoprisms and Fluorophores in Chiral Cellulose Nanocrystal Films

Abstract

Amplification of the intensity and dissymmetry factors (glum) of circularly polarized light is desired to broaden the range of applications of circularly polarized luminescence (CPL) because of the small glum values commonly observed for CPL materials and the loss of intensity resulting from circular polarization. In this study, enhanced CPL produced by metal‐enhanced fluorescence is successfully achieved by the self‐assembly of Au@SiO2 triangular nanoprisms (Au@SiO2TNPs) and fluorophores (sulforhodamine 101 and methylene blue) in chiral cellulose nanocrystal films. By overlapping the plasmon bands of Au@SiO2TNPs and the excitation–emission spectra of fluorophores, both the fluorescence intensity and glum value of CPL are significantly enhanced. For sulforhodamine 101 in the metal‐enhanced CPL system, a 52‐fold fluorescence enhancement is achieved, and the glum value increased from −0.038 to −0.126. For methylene blue in the metal‐enhanced CPL system, a 201‐fold enhancement of fluorescence is obtained, and the glum value is enhanced from −0.055 to −0.085. This metal‐enhanced CPL film is expected to generate superior circularly polarized light for extensive CPL applications because of its outstanding enhanced CPL, fluorescence amplification, and feasibility for different fluorophores.

Exploring the Core Parameters of CNC-Based Chiral Nematic Structures for Enhancing the Dissymmetry Factor of Right-Handed Circularly Polarized Luminescence

“…Based on the definition of g lum factor, g lum = 2 × ( I L – I R )/( I L + I R ), the different enhancements of LCP and RCP will lead to the increase of the g lum factor. In the previous study of MB with Au@SiO 2 triangular nanoprisms, a 201-fold enhancement of the MB fluorescence intensity has been achieved, and the g factor was changed from −0.055 to −0.085 …”

“…The MB@ CNC5 single-layer device showed a g lum factor of −0.153 at 677 nm, which is much higher than that reported in the literature, |g lum | 0.055−0.085 in the case of MB absorbed on Au@SiO 2 triangular nanoprisms and co-assembled with CNCs. 46 For the Si QD series, the g lum was −0.156 at 490 nm, similar to that of the MB case, but it is lower than the literature report (−0.25). 4 R6G@CNCs single-layered devices with different thicknesses have been compared (Figure S3).…”

Biomolecule‐Based Circularly Polarized Luminescent Materials: Construction, Progress, and Applications

“…[124] Gao et al realized metalenhanced CPL thin films by the self-assembly of Au@SiO 2 triangular nanoprisms (Au@SiO 2 TNPs) and fluorophores (sulforhodamine 101 and methylene blue) in chiral cellulose nanocrystalline films. [125] In another work, they further developed the system and proposed novel dual-mode CP light-emitting films with MEF realized by the light emitter-AuTNP/CNC interface. Left-and right-handed CPL emission can be realized by directly exciting the back and front of the bilayer film.…”

Air‐tolerant upconverted circularly polarized luminescence enabled by confined space of chiral micelle

“…Realizing the practical application requires a relatively large g lum value, which remains the most important issue in this field. To date, various strategies have been proposed, including supramolecular self-assembly, [20][21][22][23] energy transfer, [24][25][26][27] charge transfer, 28,29 aggregation-induced emission (AIE), [30][31][32][33] and so on. In previous work, tripletenergy transfer and annihilation-based photon upconversion have been demonstrated as a general and effective strategy to amplify the circular polarization of luminescent annihilators.…”