A combinatorial approach to the discovery and optimization of YCa4O(BO3)3-based luminescent materials

Thin films of YCa4O(BO3)3 (YCOB)-based new luminescent materials were explored by the combinatorial pulsed laser deposition (PLD) method which enabled us to fabricate continuous composition spread film libraries. Strong red and green luminescence were found in the Y1−xEuxCOB (0 ≤ x ≤ 1), (YEuCOB) and Y1−yTbyCOB (0 ≤ y ≤ 1) (YTbCOB) films, respectively. The film libraries were characterized by photoluminescence (PL), PL decay, an electron-probe microanalyzer and an electron diffraction analysis. The luminescent intensities in the amorphous film libraries strongly depended on the chemical composition of each rare-earth (RE) ion. The optimum concentration of rare-earth ions in YEuCOB and YTbCOB were experimentally determined to be Eu = 7.5% and Tb = 20-30%, respectively.