Transparent Inverted Organic Light-Emitting Diodes with a Tungsten Oxide Buffer Layer

Highly efficient transparent OLEDs are demonstrated. A novel WO3 buffer layer protects the organics during the sputter deposition of the top ITO electrode. L-J-V and SIMS analysis yield optimized devices with a 60 nm thick WO3 layer. Very high efficiencies of 38cdA(-1) and 30 lm W-1 at 100 cd m(-2) are obtained. At the same time the transmittance throughout the visible part of the spectrum exceeds 75%.