Excellent hydrophobic property of K3AlF6:Mn4+ phosphor by coating with reduction graphene oxide on the surface of materials

Poor water resistance of Mn4+ doped fluoride red phosphors limit their practical applications in optical devices. Reduction graphene oxide (rGO) is well known as a hydrophobic material. By coating with rGO on K3AlF6:Mn4+ phosphor, the moisture resistance performance of the phosphor is significantly improved. It was found that after being aged at high temperature (85 °C) and high humidity (85%) at atmosphere for 720 h (30 days), the emission intensity of modified phosphors is at 91% (100 ppm rGO), 83% (80 ppm rGO), 60% (60 ppm rGO), 43% (40 ppm rGO), 27% (20 ppm rGO), and 25% (10 ppm rGO), from its initial value, which are about 3.78, 3.46, 2.50, 1.79, 1.13, and 1.05 times higher than 24% of non-coating rGO products. The WLEDs fabricated with K3AlF6:Mn4+@rGO phosphor show excellent color rendition with lower color temperature (3081 K), higher color rendering index (CRI, Ra = 89.0, R9 = 82.7). Thus, K3AlF6:Mn4+@rGO phosphor is a potential candidate for commercial applications of phosphors in the future. •A novel K3AlF6:Mn4+@rGO phosphor was synthesized.•Effects of rGO on optical properties of K3AlF6:Mn4+ have been investigated.•K3AlF6:Mn4+@rGO exhibited high thermal stability, high humidity stability.•The WLED using K3AlF6:Mn4+@rGO exhibited high CRI (Ra = 89.0, R9 = 82.7).