Opto-electronic properties of novel helical conjugated polymers

Helical conjugated polymers are of great interest for their potential applications including as circularly polarized light emitters and as magnetic field sensors. Due to their relatively strong absorption cross sections and high emissivity, these materials permit a detailed investigation of how the transition between helical and random coil forms are driven by polymer structural features such as chain length and chemical defects and extrinsic properties such as solvent and temperature. Recently the Noonan group synthesized a helical polyfuran and its chiral analog (poly(3ethylhexylesterfuran) or P3HEF and (S)-poly(3ethylhexylesterfuran) or S-PEHEF). P3HEF is a tightly folded helix with nearly crystalline properties whereas S-P3EHEF exhibits a helix-coil transition temperature that is solvent tunable. Single-particle microscopy is used to probe this transition and to determine whether the conformations favored in solution are retained in the solid state. Ultrafast spectroscopy, spectro-electrochemistry and electrochemical transistor measurements are used to probe charge separation and transport in the thin films over a range of timescales.