(Received June 29, 2000; accepted for publication July 21, 2000)
We have demonstrated a patterned organic light-emitting device fabricated by screen-printing on the basis of the doped hole-transport layer (DHTL) which is our novel concept. The DHTL, which consisted of a polymeric compound of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (P-TPD) as a hole-transport material and tris (4-bromophenyl) aminium hexachloroantimonate (TBAHA) as an electron-accepting dopant, was patterned by screen-printing. The luminous area of the device was restricted to the DHTL-printed area. The device was operated at approximately 5 V, and a luminance of 4800 cd/m2 was obtained at a current density of 150 mA/cm2. The appropriate concentration of P-TPD was 80 g/l in dichlorobenzene, at which a smooth and pinhole-less layer was obtained with a thickness of 0.5 µm. The suitable concentration of TBAHA in P-TPD was approximately 8 wt%.
KEYWORDS:screen-printing, patterning, organic light-emitting diode, doped organic light-emitting diode, doped hole-transport layer