Cellulose Acetate Butyrate Films as a Platform for Energy Upconversion Composites: Design and Properties

This study presents the development of composite films made from cellulose acetate butyrate (CAB) incorporating NaYF₄:Yb³⁺,Er³⁺ upconversion particles. The films were synthesized by using a solvent casting method, focusing on optimizing their structural, thermal, and luminescent properties. The upconversion particles were produced via a hydrothermal method and then surface-modified using nitrosonium tetrafluoroborate (NOBF₄) to enhance dispersion in polar solvents. Including upconversion particles notably increased the luminescence performance of the films, while adding Tween 80 and dioctyl sodium sulfosuccinate (DSS) significantly improved mechanical and optical characteristics. The structural, morphological, and luminescence properties were thoroughly evaluated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and photoluminescence spectroscopy. Results demonstrated a uniform distribution of particles with well-preserved upconversion properties, revealing that Tween 80 contributed to a higher luminescence intensity than DSS. These findings underscore the potential of CAB-based composites in photonic device applications, offering a promising avenue for advancing energy conversion technologies.