導電性シリコーン材料の発見（A Rule-Breaking, Colorful Silicone That Could Conduct Electricity）

2025-05-24

2025-05-22 ミシガン大学

Test tubes containing the new silicone copolymers, separated by chain length, from long to short provide visual evidence of the varying band gap in the new semiconductor silicone. Shining a UV light creates a rainbow of beakers as the longer chain lengths shift towards the red end of the electromagnetic spectrum, requiring less energy to absorb and emit light at lower energies. Image credit: Zijing (Jackie) Zhang.

ミシガン大学の研究チームは、従来絶縁体とされていたシリコーンを導電性材料へと変換する新技術を開発しました。この革新的なアプローチでは、シリコーン分子内のケイ素と酸素の結合角度を調整することで、電子の移動経路を形成し、電気伝導性を実現しています。さらに、このシリコーンは多彩な色彩を持ち、柔軟性や耐熱性を保持しながら、電子機器やウェアラブルデバイスへの応用が期待されています。この発見は、従来のシリコーンの用途を拡張し、電子工学や材料科学の分野で新たな可能性を開くものとされています。

＜関連情報＞

Si─O─Si結合におけるσ-σ共役反応 σ–σ conjugation Across Si─O─Si Bonds

Zijing Zhang, Cecilia Pilon, Hana Kaehr, Pimjai Pimbaotham, Siriporn Jungsuttiwong, Richard M. Laine
Macromolecular Rapid Communications Published: 12 March 2025
DOI:https://doi.org/10.1002/marc.202500081

Abstract

Polysiloxanes and silsesquioxanes (SQs) are known to be insulating materials. We describe here polysiloxane copolymers where this is not the case. Thus,Me₂VinylSi─O─SiMe₂Vinyl/Br-Ar-Br copolymers exhibit conjugation via Si─O─Si bonds contrary to the widespread understanding that such linkages must be insulating. Here we describe the synthesis, characterization, and photophysical properties of [-VinylSiMe₂OMe₂SiVinyl-Ar]x copolymers; Ar = phenyl, terphenyl, stilbene, thiophene, etc. Con-jugation is evidenced by redshifted emission λ_max of copolymers vs model compounds, [(MeO)₂SiMeVinyl-Ar-VinylMeSi(OMe)₂], electron transfer to F4TCNQ and MW (DP) depend-ent emission red-shifts (smaller bandgaps with increasing DP). Theoretical calculations targeting electronic structure, absorbance/emission λ_max of model com-pounds vs oligomers support conjugation via π-dπ^* orbital interactions. In the ground state, model compounds offer Si─O─Si bond angles of ≈110° on average. In the copolymers, bond angles change in the ground state averaging ≈ 140 ° and in the excited state approach 150 ° much closer to planarity, a result of conjugation. Here SiOSi bonds facilitate intersystem charge transfer (ICT) as seen in carbon based polymers. Thus, i.e, ICT in VySiOSiVycoPh likely leads to a much larger Stokes shift (≈115 nm) than in the silane model. Our findings provide the first detailed photophys-ical studies of conjugation in polysiloxane-chromophore copolymers.