Uncovering the Circular Polarization Potential of Chiral Photonic Cellulose Films for Photonic Applications

TLDR

Circularly polarized light is central to photonic technologies, yet scalable generation of CPL with tailored chiroptical activity from low‑cost raw materials remains a key challenge. This study shows that cellulose films with photonic bandgaps and left‑handed helices can intrinsically produce circularly polarized light with high |g| values, defined handedness, and tunable wavelength. By evaporation‑induced self‑assembly of cellulose nanocrystals, the authors create scalable photonic bandgap films whose nanoscale mesogens enable PBG‑driven stimulation of right.

Abstract

Abstract Circularly polarized light (CPL) is central to photonic technologies. A key challenge lies in developing a general route for generation of CPL with tailored chiroptical activity using low‐cost raw materials suitable for scale‐up. This study presents that cellulose films with photonic bandgaps (PBG) and left‐handed helical sense have an intrinsic ability for circular polarization leading to PBG‐based CPL with extraordinary | g | values, well‐defiend handedness, and tailorable wavelength by the PBG change. Using such cellulose films, incident light ranging from near‐UV to near‐IR can be transformed to passive L‐CPL and R‐CPL with viewing‐side‐dependent handedness and | g | values up to 0.87, and spontaneous emission transformed to R‐CPL emission with | g | values up to 0.68. Unprecedented evidence is presented with theoretical underpinning that the PBG effect can stimulate the R‐CPL emission. The potential of cellulose‐based CPL films for polarization‐based encryption is illustrated. The evaporation‐induced self‐assembly coupled with nanoscale mesogens of cellulose nanocrystals opens new venues for technological advances and enables a versatile strategy for rational design and scalable manufacturing of organic and inorganic CPL films for photonic applications.