High efficiency organic light-emitting devices with Al/NaF cathode

An organic light-emitting device (OLED) with an Al/NaF (1.5 nm) cathode exhibited a highly enhanced performance comparable to the one with the best Al/LiF cathode. This suggests that NaF can be an alternative to commonly used LiF interlayer for improved OLED performance. Photoelectron spectroscopy studies revealed that the intensity of the gap states and the amount of the valence band shift at Al/NaF/Alq3 interface surpassed those of Al/LiF/Alq3 interface, suggesting that the observed performance improvement is directly related with these features.