pH dependent hydrothermal synthesis of Ca14Al10Zn6O35:0.15Mn4+ phosphor with enhanced photoluminescence performance and high thermal resistance for indoor plant growth lighting

Artificial light source for indoor cultivation has been vastly impeded by the lack of high far red emitting phosphors. Recently, Mn4+ activated phosphors were reported to be promising luminescent materials to solve above matter. In this study, controllable design of Ca14Al10Zn6O35:0.15Mn4+ (CAZO:0.15Mn4+) far red emitting phosphors was realized via pH assisted hydrothermal approach. The pure CAZO:0.15Mn4+ phosphors were obtained merely when the reaction pH was 1 or 2. Meanwhile, by adjusting the pH value of the reaction solution, far red emission CAZO:0.15Mn4+ phosphors with grains, sphere-like as well as aggregated bulk particles can be achieved at pH = 4, pH = 6 and pH = 10, respectively. Furthermore, the structures and morphologies depended photoluminescence (PL) performances of CAZO:0.15Mn4+ were checked. The best PL performance was found for the phosphor produced at pH = 6, while over acidic or alkaline conditions would lower the emission intensity. In addition, this phosphor also exhibit good thermal resistance which can maintain 78% initial intensity at 150 °C. The practical indoor tobacco cultivation demonstrated that CAZO:0.15Mn4+ obtained through this pH adjusted hydrothermal route is a promising phosphor for indoor plant growth lighting.