Sequential in-situ growth of layered conjugated polymers for optoelectronics under electrochemical control.

Abstract

Layered optoelectronic devices are manufactured using multistep procedures that require high precision in the spatial positioning of individual materials. Current technology uses costly and tedious procedures and instrumentation. In this work instead, we propose an approach which exploits the fundamental properties of the substrate to direct the growth of the next layer, here controlled by an electrochemical potential. We have electrochemically synthesized and characterized a series of polymeric materials that are most commonly used in the field. The films produced show gradient monomer ratios embedded in the polymeric film as a function of the distance from the working electrode. Under the optimized conditions, reproducible construction of simple electronic elements, e.g., rectifying diodes, is achieved. We argue that the sequential in situ method leads to gradient composition of polymer chains and the film resulting in the rectification of electric current. We discuss how this system can open new avenues in advanced optoelectronic applications, such as organic light-emitting diodes (OLEDs) or field-effect transistors (OFETs).