Single-layer organic light-emitting diodes using naphthyl diamine

Abstract

N, N′ -diphenyl- N, N′ -bis(1-naphthyl) (1, 1′ -biphenyl)- 4, 4′ diamine (NPB), a common hole transporter, was employed to fabricate single-layer organic light-emitting diodes (OLEDs). With a quasi-Ohmic anode, NPB device exhibited a bulk-limited hole current in the low-voltage region. Electron injection and light emission were clearly observed for applied voltages exceeding 4 V. In order to confine the recombination zone, intentional doping was applied to the single-layer device. After doping with perylene, the luminance and current efficiency of NPB device increased dramatically. It is expected that more efficient single-layer OLEDs can be achieved by using the doping strategy. © 2007 American Institute of Physics.