Li₂SrSiO_4: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 ¹D₂ → ³H₄ 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 ¹G₄ → ³H₄ 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.