Photopatterned electrochromic conjugated polymer films via precursor approach

Herein we report the photolithography of electrochromic conjugated polymer (CP) films on the micron scale without exposing the CP to high energy UV radiation. The synthesis of polynorbornene-based precursor copolymers having units with pendant terthiophenes and photocrosslinkable units allows for photopatterning at an earlier stage with respect to the polymerization (chemically or electrochemically) that yields the conducting polymer. The effect that the composition of the photocrosslinkable unit has on the overall process was studied, showing no effect on the electrochemical and optical performance of the conducting polymer. Electrochromic photopatterned structures down to 1 μm were obtained, together with some basic structures for microelectronics. This technique does not have any specific substrate restrictions, and can be used to pattern conducting polymers on flexible, rigid, conducting, or insulating substrates using the present photolithography facilities available to industry and academia.