Photothermal response and precise control of circularly polarized luminescence double-layered films based on cholesteric liquid crystals

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 13; no. 13; pp. 6641 - 6649
• Main Authors: Huang, Sha, Wu, Qimei, Hu, Yongjie, Wang, Xincan, Yuan, Yongjie, Zhang, Hailiang
• Format: Journal Article
• Published: 27.03.2025
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d5tc00064e

The regulation of the performance of circularly polarized luminescence (CPL) materials has long been a subject of considerable interest. However, achieving simultaneous photothermal responsiveness and precise control of CPL performance remains a challenge. To address this issue, a double-layered film strategy is employed, where the overlap between the emission band of a luminescent layer, exhibiting non-polarized or circularly polarized luminescence, and the selective absorption and reflection bands of a cholesteric liquid crystal (N*-LC) layer with stimuli-responsive properties is utilized to achieve photothermal response and precise regulation of CPL performance. The non-chiral luminescent compound and the CPL copolymer are used as the first layer, combined with N*-LC polymers Azo( x )-Mt( y ) synthesized in this work, to prepare the double-layered films NI/Azo( x )-Mt( y ) and Py/Azo( x )-Mt( y ). Non-polarized or circularly polarized fluorescence is emitted from the first-layered film upon light excitation, allowing static regulation of CPL performance after passing through selective absorption and selective reflection of the second-layered N*-LC film. Additionally, the CPL signals of double-layered films are further precisely regulated in terms of on-off, inversion, intensity, and wavelength by adjusting the Azo( x )-Mt( y ) copolymer composition. Furthermore, under different photothermal conditions, the CPL wavelength and intensity of double-layered films are dynamically regulated by stimulating Azo( x )-Mt( y ), as azobenzene mesogens undergo trans - cis isomerization. A double-layered film strategy is used, where the emission band of a luminescent layer overlaps with the selective absorption and reflection bands of a N*-LC layer, enabling photothermal response and precise control of CPL performance.