Preparation and properties of Sr2Si5N8:Eu2+–cellulose hybrid films for sunlight conversion

Sr₂Si₅N₈:Eu²⁺–cellulose hybrid films were successfully prepared, by use of a green sol–gel transition method, from cellulose and a sunlight-conversion agent. Cellulose quickly dissolved in 7 wt% NaOH–12 wt% urea aqueous solution at low temperature, as a result of a fast dynamic self-assembly process. The Sr₂Si₅N₈:Eu²⁺ particles were embedded firmly in the cellulose matrix, as a consequence of a strong interaction between the cellulose and the particles. Results from scanning electron microscopy, absorption spectroscopy, fluorescence spectroscopy, and tensile testing confirmed the hybrid films had a homogenous structure, wide absorption, strong fluorescence emission, and good tensile properties. Moreover, fluorescence spectroscopy confirmed that the excitation and the emission intensity of films were related to the concentration of the Sr₂Si₅N₈:Eu²⁺. The mechanical properties could be improved by adjustment of the concentration of Sr₂Si₅N₈:Eu²⁺. This work has provided a new method for preparation of sunlight-conversion films; the process has potential for large-scale application and is expected to be used in greenhouse planting.