This study presents a straightforward approach to enhancing the light energy capture and storage properties of cellulose acetate/azobenzene (CA/Azb) films through photosensitization with a perylene derivative (Py). The films' photoisomerization (trans-to-cis) and reverse isomerization (cis-to-trans) behaviors were evaluated under cold white LED light. Incorporating varying concentrations of perylene significantly improved the films' optical performance and energy storage capacity. Notably, the photoisomerization time of CA/Azb/Py films decreased by up to 30% compared to CA/Azb films. Furthermore, the energy storage half-life for films with the highest perylene content reached 70 minutes, substantially longer than that of CA/Azb films (24 minutes). Remarkably, the energy density of the film with the highest perylene content reached 240 J g-1, which is more than 1.7 times higher than that of the CA/Azb film (138 J g-1).