Electrode Patterning for Organic Diodes by Roll-to-Roll Processes

A roll-to-roll (R2R) photo-lithographic process using a negative dry film photo-resist was used to pattern ITO on a PET film. The roll type of PET film with patterned ITO was used as one of the electrodes for printed organic diodes fabrication. The web width of the roll-to-roll manufacturing line is 250 mm and the speed can be adjusted from 1 m/min to 3 m/min. The patterned ITO electrode made by the R2R photo-lithographic process showed a feature size less than 10 mum. A polymer diode device was fabricated by coating a polymer conductor and semiconductor on the patterned ITO electrode followed by thermal evaporating a cathode electrode on the semiconductor layer. The diode DC transfer curve showed a Vt at around 0.5V and a ON/OFF ratio above 104. These results demonstrated the feasibility of using the R2R processes for fabricating organic electronics devices.