Organic light-emitting diodes with n-type silicon anode

In an AlQ-based bilayer organic light-emitting diode, n-type silicon has been used as an anode, and semitransparent metals Sm (15 nm)/Au (15 nm) as a cathode. This device has much smaller currents at high voltages (>8 V) and a higher turn-on voltage than the device with an identical structure but an indium–tin oxide anode. By successively depositing ultra thin films of Au and AlQ on the n-Si surface, the device performances are improved significantly, reaching a power efficiency of 0.1 lm W −1 and a current efficiency of 0.7 cd A −1 at 15.9 V and 0.3 mA mm −2 . The mechanisms for the hole injection and performance improvement are discussed.