VUV spectroscopy of luminescent materials for plasma display panels and Xe discharge lamps

Abstract

In plasma display panels and Xe discharge lamps, phosphors with a high quantum efficiency under vacuum ultraviolet (VUV) excitation are required. Absolute quantum efficiencies of such phosphors are usually be determined by using synchrotron radiation since the excitation wavelength can be freely tuned over a wide energy range. A serious drawback of the use of synchrotron radiation for this purpose is the accessibility towards research facilities and the time-consuming measurement procedure which is not in line with the fast pace of industrial phosphor development. We have built up a VUV spectrophotometer which allows the measurement of absolute excitation and reflection spectra in the wavelength range of 115–350 nm. Additionally, a procedure was developed to derive spectrally resolved quantum efficiencies from these excitation spectra. In this work, the set-up of the VUV spectrometer is described and its performance is documented by comparing the obtained light output data of several phosphors with results recorded by using synchrotron radiation. It is shown that also a relatively simple VUV spectrometer can be used to determine absolute light output and quantum efficiency data in the excitation range between 115 and 350 nm with an experimental error lower than 10%.