AN ORGANIC ELECTROLUMINESCENT DOT-MATRIX DISPLAY USING CARBON UNDERLAYER

A carbon layer has been inserted between ITO and a hole-transport laye r in an organic electroluminescent (EL) device with the aim of improvi ng its stability and efficiency, The structure of the proposed device is ITO/carbon/hole-transporting material/Alq3+dopant/cathode (AI-Li). The carbon layer is quite effective for improving the threshold voltag e and the contrast, These advantages are explained in terms of ionizat ion potentials, effectiveness in adhesion and its light absorption. By using the carbon layer, an EL display panel with 16 x 96 dots has bee n fabricated, The display exhibits excellent performance: a half decay period of 4000 h at an initial luminance of 500 ed cm(-2) and strong and pure green emission, In addition, no dark spots are detectable dur ing the operation. (C) 1997 Elsevier Science S.A.