Development of inorganic electroluminescent displays at SVA

Improved dielectric and phosphor materials and device structures for thin film electroluminescent (TFEL) displays are reported. With a combination of Al2O3, Ta2O5, SrTiO3, BaxSr1-xTiO3, ZrO2 and HfO2 thin films etc., prepared by RF or pulsed-DC reactive magnetron sputtering, or by electron beam evaporation, high performance composite thin film dielectrics with a figure of merit greater than 10 mu C/cm(2) have been successfully developed and used as lower and upper dielectrics in ZnS: Mn and Zn2SixGe1-xO4: Mn based TFEL devices. High luminance at 50 V above the threshold (L-50) has been achieved for the ZnS: Mn based TFEL devices with L-50 = 882 cd/m(2) at V-th = 170 V, when driven by 200 Hz AC voltage. 2-inch diagonal monochrome TFEL displays ( 128 x 64 pixels) based on the novel dielectric stacks have been successfully developed which are capable of displaying scrolling messages. L-50 has reached 488 cd/m(2) for the 2-inch diagonal (128 x 64 pixels) monochrome TFEL displays when driven by 200 Hz AC voltage. Finally, efforts towards the development of full-color TFEL displays are discussed, including the development of BaAl2S4: Eu based blue-emitting TFEL phosphor and the color change materials (CCM).