Improving the efficiency of a blue-emitting phosphor by an energy transfer from Gd3+ to Ce3+

The low-voltage efficiency of the blue-emitting phosphor, cerium activated yttrium silicate (Y1−mCem)2SiO5, has been improved by co-activating with gadolinium, (Y1−m−nCemGdn)2SiO5. Gd3+ improves the efficiency by transferring energy to Ce3+, and makes this phosphor a more promising candidate for low-voltage field emission flat panel displays. Low-voltage cathodoluminescence and photoluminescence measurements were made to determine the optimum concentrations of Gd3+ that yielded the most luminous efficient phosphor. For photoluminescence, Ce3+ most efficiently luminesces at the excitation wavelength λex=358 nm. Co-activating with Gd3+ did not improve the photoluminescent efficiency because Gd3+ does not absorb at Ce3+ excitation energy, and thus cannot transfer energy. For low-voltage cathodoluminescence, co-activating with Gd3+ did improve the efficiency since Gd3+ was sufficiently excited, with the optimum composition found to be (Y0.8425Ce0.0075Gd0.15)2SiO5.