Efficient, blue light-emitting diodes using cross-linked layers of polymeric arylamine and fluorene

Single-, double- and triple-layer polymer light-emitting diodes (PLEDs) wit h indium-tin oxide (ITO) anodes and Ca cathodes were fabricated, based on s olution processable and thermally cross-linkable hole transporting polyaryl amine and blue luminescent polyfluorene; and an electron transporting oxadi azole trimer. Triple-layer PLEDs show the highest efficiency, brightness an d saturation of blue emission. These results are interpreted in terms of ch arge injection balance and electron-hole recombination efficiency. The maxi mum external quantum efficiencies achieved (> 1%) are comparable to the bes t polymer blue PLEDs. (C) 1999 Elsevier Science S.A. All rights reserved.