2010•Chemistry of MaterialsRequires access
Energy-Efficient, High-Color-Rendering LED Lamps Using Oxyfluoride and Fluoride Phosphors
Anant Setlur, Emil Radkov, Claire S. Henderson, Jae‐Hyuk Her, A.M. Srivastava, Nagaveni Karkada, M. Satya Kishore, N. Prasanth Kumar, Danny Aesram, Anirudha Deshpande, Boris Kolodin, L. Grigorov, U. Happek
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Abstract
LED lamps using phosphor downconversion can be designed to replace incandescent or halogen sources with a “warm-white” correlated color temperature (CCT) of 2700−3200 K and a color rendering index (CRI) greater than 90. However, these lamps have efficacies of ∼70% of standard “cool-white” LED packages (CCT = 4500−6000 K; CRI = 75−80). In this report, we describe structural and luminescence properties of fluoride and oxyfluoride phosphors, specifically a (Sr,Ca) 3 (Al,Si)O 4 (F,O):Ce 3+ yellow-green phosphor and a K 2 TiF 6:Mn 4+ red phosphor, that can reduce this gap and therefore meet the spectral and efficiency requirements for high-efficacy LED lighting. LED lamps with a warm-white color temperature (3088 K), high CRI (90), and an efficacy of ∼82 lm/W are demonstrated using these phosphors. This efficacy is ∼85% of comparable cool-white lamps using typical Y 3 Al 5 O 12:Ce 3+ -based phosphors, significantly reducing the efficacy gap between warm-white and cool-white LED lamps that use phosphor downconversion.