Protein-Assisted Assembly of π-Conjugated Polymers

In an aqueous suspension process, protein dispersions facilitated improved alignment and organization of poly(3-hexylthiophene) (P3HT) chains into highly ordered crystalline structures. A solution of P3HT in 1,2,4-trichlorobenzene (TCB) was added to an aqueous dispersion of the hydrophobin, Cerato ulmin (CU). Upon gentle agitation, the semiconductor solution was readily confined within CU membrane-stabilized microstructures, often with extended shapes. UV–vis and polarized micro-Raman spectroscopy suggested complex, enhanced molecular alignment due to a transition from isotropic to liquid crystalline fluid to polycrystalline states. Grazing-incidence X-ray diffraction corroborates this interpretation. On aging, the initial CU:P3HT/TCB structures develop dendritic architectures that slowly release polymer-containing capsules. The counterintuitive evolution from large structures to smaller ones suggests the initial structures were nonequilibrium, and it opens the door to latex-like processing of semiconducting polymers into crystalline, high-performance thin films for device applications. Preliminary studies using an organic field-effect transistor architecture suggest that optimized processing and device configuration will enable highly crystalline active materials with efficient charge transport characteristics.