Enhanced luminescence properties of Li2MgTiO4: Mn4+, Ge4+ phosphor via single cation substitution for indoor plant cultivation

Abstract

Red and far-red emitting phosphors have been widely used in phosphor-converted light emitting diode (pc-LED) devices to provide lighting for indoor plant growth, thus achieving desired product qualities. Among the many ways to optimize phosphors’ optical performance, cationic substitution is one of the most effective methods. In this study, red phosphors (Li 2 MgTi 1- x - y O 4 : x Mn 4+ , y Ge 4+ ) were synthesized by high temperature solid state method and the optical performance of phosphors were improved with increasing Ge 4+ constituents. In particular, luminescence intensity of Li 2 MgTiO 4 : 0.002Mn 4+ , 0.1Ge 4+ increased by 152% under 468 nm excitation, and the thermostability of emission intensity increases from 22% ( y = 0) to 43% ( y = 0.1), which is about twice as much. Finally, pc-LED device was fabricated via the red phosphor Li 2 MgTiO 4 : 0.002Mn 4+ ,0.1Ge 4+ coated on a 470 nm ultraviolet chip. By changing the proportion of the phosphor, the electroluminescence spectra of pc-LED device could match well with the absorption regions of plant pigments. Therefore, Li 2 MgTiO 4 : 0.002Mn 4+ , 0.1Ge 4+ phosphor has potential application in plant lighting. Furthermore, this work can offer some helpful references for improving luminescent efficiency by simply modulating the chemical composition. The luminescence intensity of Li 2 MgTiO 4 : 0.002Mn 4+ , 0.1Ge 4+ increased by 152%. The thermostability of emission intensity increases from 22% ( y = 0) to 43% ( y = 0.1), which is about twice as much. Finally, the pc-LED device could emit bright blue and red light, which matched with the absorption regions of plant pigments well.