Generating semi-metallic conductivity in polymers by laser-driven nanostructural reorganization

Conductive polymers are a key component of future flexible optoelectronic devices. To obtain a high electrical conductivity in polymers, additives or treatment based on solvents are predominantly required. While previous works illustrate the benefits of conductive polymers well, such solvent-based methods tend to undermine the controllability of the overall process. In this respect, we here propose a solvent-free strategy to achieve highly conductive polymers using laser-based heating. With the proposed approach, we show that the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin-films can be enhanced by up to three orders of magnitude. Using the difference in photon absorption, the proposed method heats up PEDOT cores selectively and then transfer their heat energy to the PSS nanoshells surrounding them. In this way, insulative PSS shells are fragmented to promote nanoscale reorganization that enhances the physical contacts between adjacent PEDOT cores for improved transport pathways. Furthermore, various patterns with desired conductivities can be easily formed thanks to the spatially resolvable character inherent to the laser process. By using this laser-treated PEDOT:PSS, the authors demonstrate organic optoelectronic devices including organic photovoltaic cells and flexible force touch sensors, illustrating the versatile potential of the proposed approach in the field of transparent electronics and organic optoelectronics.