Li2SrSiO4:Ce3+, Pr3+ Phosphor with Blue, Red, and Near-Infrared Emissions Used for Plant Growth LED

Ce3+/Pr3+ codoped Li2SrSiO4 (LSS) phosphors with blue, red, and near-infrared (NIR) tri-emission have been prepared via a high-temperature solid-state reaction method. Under the excitation of 200 to 400 nm near-ultraviolet (n-UV), the photoluminescence (PL) spectra of phosphors are composed of visible and NIR two parts. The former exhibits blue and red emission bands centered at around 428 nm from 5d-4f transition of Ce3+ and 611 nm from D-1(2) H-3(4) transition of Pr3+, those overlap with photosynthesis action spectra of plants and absorption spectra of chlorophylls and carotenoids. While the later presents a broad NIR emission band peaking near 1039 nm caused by the (1)G(4) H-3(4) of Pr3+, matching with the absorption of bacteriochlorophyll. Their emission intensity ratios (B: R: NIR) could be tuned by altering the relative ratios of Ce3+ and Pr3+ concentration in the phosphors to meet the requirements of multifarious plants and bacteria. The efficient energy transfer from Ce3+ to Pr3+ takes place in the LSS host, which ascribed to an exchange interaction according to PL spectra and decay curves of phosphors. Results suggest that the present LSS: Ce3+, Pr3+ phosphors have great potential applications in plant growth n-UV LED.