Synthesis and Optical Characterization of Annatto (Bixa orellana L.)-Doped PVDF Samples: Ultraviolet Optical Absorption Enhancement and Bandgap
DOI:
https://doi.org/10.12974/2311-8717.2026.14.08Keywords:
PVDF, Bixa orellana L., Optical bandgap, Ferroelectric polymer, UV absorptionAbstract
In this work, samples of PVDF/Annatto (PVDF/An) were synthesized and characterized as a function of annatto concentration. The FT-IR results show the incorporation of An in the polymeric matrix, without changing the relative percentage of the β phase. The UV optical properties were studied by the UV-Vis technique. The addition of An to PVDF changes the optical absorption in the UV region from 200 nm to 650 nm. The optical transmittance decreases from 60% for PVDF/An 0% to 0% for PVDF/An 5% at 540 nm. The optical absorption edge is redshifted from 251 nm to 645 nm, and the width at half weight increases approximately 1083 %, reaching 355 nm. For doped samples, the extinction coefficient presents two peaks at 470 nm and 499 nm, which might be associated with bixin. Skin depth results show a 64% decrease in Ecut-off from 6.18 eV to 2.50 eV. The addition of An shifts the optical bandgap toward lowest energies. Urbach energy decreases as An content increases. This result is consistent with the results observed for the absorption edge and the optical bandgap. Finally, the obtained results show that PVDF/An samples are potential candidates for optical and photonic applications.
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