Self-Aligned Multifunction Diodes Using Ink-Jet Printing Method

We have investigated self-aligned multifunction diodes (SA-MFDs) using an ink-jet printing (IJP) method. The MFD is defined as the diode exhibits functions of emission and photo-sensing. A special organic material of pyrazoline derivative was dissolved and a solution was printed on a transparent indium-zinc-oxide (IZO) coated glass substrate covered with an insulating poly-methylmethacrylate (PMMA) layer. The PMMA was dissolved in a solvent. Then, organic materials were formed at the same position as that of the ink-jet-printed region, that is, SA-MFD was realized. For light emitting operation, a luminance obtained was 810 cd/m2 under forward-biased condition. For photo-sensing operation under xenon lamp illumination, a photocurrent density was 0.84 µA/cm2 and the ratio of photoconductivity to dark conductivity was 102 under reverse-biased condition.