Deposition and post-treatment of promising poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate composite films for electronic applications

In this work, innovative composite films were deposited using as a matrix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) and particles of difluoroboron β-diketonate complexes, with different substituents in their periphery as a reinforcement. The composite films were treated with isopropanol (IPA) steam, with the purpose of decreasing the optical bandgap and increasing charge transport in the films. The composite films were characterized by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The bandgap was evaluated for each film before and after post-treatments, and finally, the electrical behavior was evaluated under different light irradiation conditions. To evaluate the electrical properties of the films, simple devices were manufactured. The particles of difluoroboron β-diketonate complexes with high-polarity substituents and high electron-acceptor capabilities favor the formation of composite films with low energy transitions of free carriers to higher levels within the same band, as well as those of higher energies, corresponding to the optical bandgap. Additionally, the distribution of this type of particles in the PEDOT:PSS allows, after post-treatments, the tautomerization of the structure in the polymer from benzoid to quinoid, which also favors charge transport and ohmic behavior in the devices.