A Water-Soluble Polythiophene for ‘Green ’ Organic Electronics

1. CNMS Staff Science Highlight A Water-Soluble Polythiophene for ‘Green’ Organic Electronics Scientific Achievement Water-soluble conducting polymers were synthesized and processed into field-effect transistors, demonstrating the possibility of solution processing of polymers into “green” organic electronics using water as a non-toxic solvent. The polymers (poly(thiophene) derivatives) were rendered water soluble by the addition of hydrophilic side groups. Significance Solution-processing of polymers, envisioned for low-cost organic electronics of the future, have typically relied upon toxic organic solvents such as chlorobenzene or chloroform to solubilize conducting polymers. This work demonstrates a safe and environmentally-friendly pathway toward fully ‘green’ organic electronic devices for our nation’s future energy needs. Research Details • Synthesis and characterization of novel conductingpolymers. The novel water-soluble polythiophene derivative was synthesized using Kumada catalyst transfer polymerization. P3TEGT = poly(3-(2-(2-methoxyethoxy) ethoxy)ethoxy) methylthiophene) was synthesized with a hydrophilic tri-ethylene glycol side group (see Figure). • Organic electronic device fabrication and characterization. ‘Green’ solvent processing and annealing techniques were developed to fabricate working thin-film organic field-effect transistors (OFETs) in order to understand how electrical performance correlates with film nanoscale morphology and structure. Tapping mode AFM (1 mm × 1 mm x 2 nm) height image showing the nanofibrillar morphology of a polythiophene-derivative conducting polymer film processed and annealed from water solution , exhibiting a high degree of long range order. Insets show the hydrophilic tri-ethylene glycol side-group-functionalized polythiophene, and the electrical performance of the field-effect transistor. M. Shao, Y. He,K. Hong, C. M. Rouleau,D. B. Geohegan,K. Xiao Polym. Chem., DOI:10.1039/C2PY21020G (Invited)