Polymerization of Solid-State 2,2′-Bithiophene Thin Film or Doped in Cellulose Paper Using DBD Plasma and Its Applications in Paper-Based Electronics

We present a method to prepare a conductive paper hybrid based on the polymerization of bithiophene monomer directly from the solid state of 2,2′-bithiophene inside a sheet of standard letter paper using atmospheric plasma since both the monomers and some plasma species, such as radicals, can penetrate into the paper. Polymerization of a 2,2′-bithiophene in its solid form using plasma offers a simple and straightforward way to synthesize a conductive polymer. To understand the polymerization reaction in atmospheric plasma, the formation of polythiophene on substrates and the reaction mechanism were investigated with Fourier-transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV–vis) spectroscopy. The kinetics of the polymerization reaction was investigated by using UV–vis, and the rate of polymerization was found to be the second-order reaction. The resulting polymer film exhibited a conductivity of 6.67 S/cm when I2 was doped in the film. The polymerization 3,3′-dibromo-2,2′-bithiophene to poly(3,3′-dibromo-2,2′-bithiophene) was also studied for comparison. The described process provides a universal yet effective method of preparing conductive polythiophene films and polythiophene inside a sheet of paper. Three devices based on the synthesized conductive paper were also presented in this work.