Effects of graphene quantum dots coating on the luminescence properties of K2SiF6:Mn4+ red-emitting phosphors

A series of K2SiF6:0.06Mn4+@ GQDs y mg/mol (KSF: K2SiF6, GQDs: graphene quantum dots) red-emitting phosphors were prepared with a simple coating method. Experimental results show that the KSF:0.06Mn4+@ GQDs y mg/mol has broad excitation bands in blue region and strong emission line bands in red region with the strongest peak at ~ 630 nm. Enhanced luminescence intensity and thermal stability induced by GQD coating are observed: (i) the integrated intensity of KSF:0.06Mn4+@ GQDs 5mg/mol is 1.32 times of that of KSF:0.06Mn4+, (ii) the integrated intensities of KSF:0.06Mn4+@ GQDs 5mg/mol at 120 and 180 °C are 1.57 and 1.26 times of that at 25 °C. Through temperature-dependent behavior measurement and stability test, it can distinctly learn that KSF:0.06Mn4+@GQDs 5 mg/mol exhibits exceptional thermal stability as well as color stability under LED-operating temperature conditions, which implies that the sample has potential applications for blue light-based warm W-LEDs.