Fused electron deficient semiconducting polymers for air stable electron transport

Abstract

Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

Recent Advances in Isoindigo‐Inspired Organic Semiconductors

“…Onwubiko et al. produced a series of polymers in which the repeating unit is the ring‐fused isoindigo structure with no single bonds (Chart 7) . Owing to their exceptional planarity, these polymers exhibit high air‐stable electron mobilities; compound 40 , based on isoindigo[7,6‐g]isoindigo, had an electron mobility of 0.03 cm 2 V −1 s −1 , while compound 41 (based on thienoisoindigo and isoindigo) had an electron mobility of 0.001 cm 2 V −1 s −1 (Table ).…”

Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors

“…Interestingly, many of these solubilizing chains are branched, or even chiral, creating a plethora of stereoisomers and diastereomers within one material batch, especially in polymers . Indeed, polymers used in organic photovoltaics (OPV) often benefit from increased solubility as well as improved self‐assembly/phase formation, directed by the chiral branched alkyl chains, which are becoming increasingly common in the field of solution‐processed devices . Additionally, chirality itself can add value to technological applications as demonstrated for liquid crystals by chiral control in NLO, chirality as giving selectivity to sensors as well as chirality detectors …”

Ladder‐Type Heteroarene‐Based Organic Semiconductors

“…Recently, McCulloch et al. reported a series of LCPs with a double‐bond‐locked rigid backbone conformation ( P10 – P12 ; Figure ) synthesized by using simple aldol condensation reaction. Neither organometallic monomers nor transition‐metal catalysts was required in the polymerization process, which provides a cheaper and more eco‐friendly synthetic route to novel LCPs.…”