White light emission and effect of annealing on the Ho3+–Yb3+ codoped BaCa2Al8O15 phosphor

• BaCa2Al8O15 phosphors codoped with Ho3+–Yb3+ have been prepared by combustion method.
• Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation.
• The sample annealed at higher temperatures emits in the pure green region.
• The colour emitted persists in the white region even at high pump power density.
• Developed phosphor is suitable for making upconverters and WLEDs.

The BaCa2Al8O15 (BCAO) phosphors codoped with suitable Ho3+–Yb3+ dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.

The upconversion emission spectra of the Ho3+/Yb3+ doped/codoped BaCa2Al8O15 phosphors with different doping concentrations of Ho3+/Yb3+ ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C.Figure optionsDownload as PowerPoint slide