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Title: High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi 4O 10, M = Ca, Sr, Ba)

The alkaline earth copper tetra-silicates, blue pigments, are interesting infrared phosphors. The Ca, Sr, and Ba variants fluoresce in the near-infrared (NIR) at 909, 914, and 948 nm, respectively, with spectral widths on the order of 120 nm. The highest quantum yield Φ reported thus far is ca. 10%. We use temperature measurements in sunlight to determine this parameter. The yield depends on the pigment loading (mass per unit area) ω with values approaching 100% as ω → 0 for the Ca and Sr variants. Although maximum quantum yield occurs near ω = 0, maximum fluorescence occurs near ω = 70 g m -2, at which Φ = 0.7. The better samples show fluorescence decay times in the range of 130 to 160 μs. The absorbing impurity CuO is often present. Good phosphor performance requires long fluorescence decay times and very low levels of parasitic absorption. In conclusion, the strong fluorescence enhances prospects for energy applications such as cooling of sunlit surfaces (to reduce air conditioning requirements) and luminescent solar concentrators.
ORCiD logo [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Shepherd Color Company, Cincinnati, OH (United States)
  3. PPG, Coatings Innovation Center, Allison Park, PA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; EE0006347
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 123; Journal Issue: 19; Journal ID: ISSN 0021-8979
American Institute of Physics (AIP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1437520