1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Energy Conversion and Storage, Technical University of Denmark3 Imaging and Structural Analysis, Department of Energy Conversion and Storage, Technical University of Denmark4 Department of Physics, Technical University of Denmark5 University of Cambridge6 Swiss Federal Institute of Technology7 Technische Universiteit Eindhoven8 Durham University
Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material1, 2, 3. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the excellent mechanical properties of certain commodity polymers. Here we investigate bicomponent blends comprising semicrystalline regioregular poly(3-hexylthiophene) and selected semicrystalline commodity polymers, and show that, owing to a highly favourable, crystallization-induced phase segregation of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor can be reduced to values as low as 3 wt% without any degradation in device performance. This is in stark contrast to blends containing an amorphous insulating polymer, for which significant reduction in electrical performance was reported4. Crystalline–crystalline/semiconducting–insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer itself.
Nature Materials, 2006, Vol 5, Issue 12, p. 950-956