Synchronous vapor-phase polymerization of poly(3,4-ethylenedioxythiophene) and poly(3-hexylthiophene) copolymer systems for tunable optoelectronic properties

Abstract

We successfully copolymerized poly(3,4-ethylenedioxythiophene) and poly(3-hexylthiophene) (PEDOT and P3HT) synchronously polymerizing two monomers in the vapor phase to give tunable bandgap, conductivity, surface morphology and water contact angles. Due to different vapor pressures and polymerization rates of the monomers, the PEDOT to P3HT ratios were kinetically controlled by adjusting the feed concentrations of monomers to the polymerization reaction chamber. Depending on the compositions of the two polymer systems, the optical bandgap of the thin PEDOT/P3HT copolymer film was controlled successfully in the 575-650 nm range. In addition, the electrical conductivity, surface roughness and water contact angle of the vapor-phase polymerized PEDOT/P3HT copolymer system changed in the range of 3.0 x 10 (2)-2.3 x 10(1) S/cm, 4.9-18.3 nm, and 34-54 degrees, respectively, correlated with the altered composition of two polymers. Tailoring the bandgap and other optoelectronic properties, the copolymerized P3HT/PEDOT film can provide tunable properties to be used not only as a hole injection layer (HIL) in organic light-emitting diodes (OLEDs) but also as a semiconductor with improved mobility in organic thin film transistors (OTFTs) and organic photovoltaics (OPVs). (C) 2010 Elsevier B.V. All rights reserved.