Helicenes are organic compounds whose ortho-fused aromatic rings give them a conjugated backbone with a spring-like helical geometry. They have attracted great interest due to this unique molecular structure, chirality and the resulting optoelectronic properties. These molecular springs has also been predicted to enable mechanical deformation without impairing charge transport along the conjugated backbone making them particularly promising candidates for deformable chiral optoelectronics in wearable devices. Helicene application in organic electronics has mostly been limited to carbohelicenes and related structures, partly due to the difficulty of developing scalable syntheses, especially for electron-deficient building blocks. In this presentation we present newly gram-scale synthesized n-type helicenes and investigate their incorporation into the backbones of conjugated polymers. By carefully tuning the helicene structure we demonstrate great tunability of energy levels, photophysical properties and helicity inversion barriers. Significantly, this tunability allows for the synthesis of helical building blocks with LUMO levels similar to common rylene acceptor units. We further present the application of these electron-deficient helicenes in donor-acceptor materials, which have been the mainstay of many areas of organic electronics in recent years. By carefully tuning monomer molecular structure and polymerization conditions, we can efficiently incorporate helical building blocks into conjugated polymers, which allows for interesting electrical, thermal and chiroptical properties towards application in OFETs and other devices.
