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Alkali metal coactivators in SrS: Cu,F thin-film electroluminescent devices

TitleAlkali metal coactivators in SrS: Cu,F thin-film electroluminescent devices
Publication TypeJournal Article
Year of Publication1999
AuthorsKeir, P. D., J. F. Wager, B. L. Clark, D. Li, and D. A. Keszler
JournalApplied Physics Letters
Date Published1999
Keywordsalkali metals, brightness, colour displays, copper, electroluminescence, electroluminescent displays, flat panel displays, fluorine, phosphors, strontium compounds, vacuum deposited coatings

A unique approach for obtaining bright and efficient saturated green phosphors for alternating-current thin-film electroluminescent (ACTFEL) device applications is presented. The approach involves color-shifting blue SrS:Cu,F ACTFEL phosphors into the green region of the spectrum via the incorporation of alkali metal ions into the SrS lattice. Alkali metals are incorporated into SrS:Cu,F phosphors by using LiF, NaF, KF, RbF, or CsF coactivators. The best result to date is obtained by using a KF coactivator and results in a saturated green brightness and efficiency of 52.7 cd/m² and 0.973 lm/W (at a frequency of 60 Hz and an overvoltage of 40 V). In addition to providing a color shift, the alkali-metal fluorides improve the overall performance of the ACTFEL device by increasing the magnitude of the electric field and its uniformity across the phosphor through suppression of positive space charge.

Short TitleAppl. Phys. Lett.