Micropatterning of organic electronic materials using a facile aqueous photolithographic process

Patterning organic semiconductors via traditional solution-based microfabrication techniques is precluded by undesired interactions between processing solvents and the organic material. Herein we show how to avoid these problems easily and introduce a simple lift-off method to pattern organic semiconductors. Positive tone resist is deposited on the substrate, followed by conventional exposure and development. After deposition of the organic semiconductor layer, the remaining photoresist is subjected to a flood exposure, rendering it developable. Lift-off is then performed using the same aqueous developer as before. We find that the aqueous developers do not compromise the integrity of the organic layer or alter its electronic performance. We utilize this technique to pattern four different organic electronic materials: epindolidione (EPI), a luminescent semiconductor, p-n photovoltaic bilayers of metal-free phthalocyanine and N,N’-dimethyltetracarboxylic diimide, and finally the archetypical conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The result of our efforts is a facile method making use of well-established techniques that can be added to the toolbox of research and industrial scientists developing organic electronics technology.