Eco‐Friendly SiO ₂ From Sugarcane Bagasse Enhance P3HT Electrochromic Devices

Harnessing the synergistic effects of composite materials enables the design of smart windows with improved performance. Furthermore, the utilization of agro‐industrial waste is desirable to promote the circular economy and contribute to environmental and health care. In this work, in situ synthesized composites based on poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and silicon dioxide (SiO 2 ) extracted from a natural source (sugarcane bagasse) are investigated. The effect of acid treatment of sugarcane bagasse fibers and variations in SiO 2 concentration in P3HT on the physicochemical properties of the compound are studied. The composites are characterized by infrared and ultraviolet–visible spectroscopy, X‐ray diffraction, cyclic voltammetry, scanning electron microscopy/energy dispersive spectroscopy, and atomic force microscopy. The results show that the properties of P3HT improve with the addition of SiO 2 extracted from sugarcane bagasse, corroborating an increase in conjugation length, polymer chain arrangement, and stored charge, as well as a decrease in the bandgap. Furthermore, the synthesized composites are tested in dual electrochromic devices (DEDs) using the GLASS/ITO/COMPOSITE/PE/PANI/ITO/GLASS configuration. DEDs show higher optical contrast and more stable optical kinetics when incorporating SiO 2 into P3HT. The addition of SiO 2 to P3HT increases the optical contrast of dual DEDs by up to 126.9%, offering an alternative for the development of electrochromic devices.