Passivated p-type silicon:: Hole injection tunable anode material for organic light emission

We find that hole injection can be enhanced simply by selecting a lower-resistivity p-Si anode to match an electron injection enhancement for organic light emitting diodes with ultrathin-SiO2-layer-passivated p-Si anode (Si-OLED). For a Si-OLED with ordinary AlQ electron transport layer, the optimized resistivity of the p-Si anode is 40 Omega cm; for that with n-doped Bphen electron transport layer, it decreases to 5 Omega cm. Correspondingly, the maximum power efficiency increases from 0.3 to 1.9 lm/W, even higher than that of an indium tin oxide control device (1.4 lm/W). This passivated p-type silicon is a hole injection tunable anode material for OLED. (C) 2008 American Institute of Physics.