Precise Control of the Molecular Arrangement of Organic Semiconductors for High Charge Carrier Mobility.
Ryota AkaiKouki OkaShun DekuraKazuyoshi YoshimiHatsumi MoriRyosuke NishikuboAkinori SaekiNorimitsu TohnaiPublished in: The journal of physical chemistry letters (2023)
Organic semiconductors are well-known to exhibit high charge carrier mobility based on their spread of the π-orbital. In particular, the π-orbital overlap between neighboring molecules significantly affects their charge carrier mobility. This study elucidated the direct effect of subtle differences in the π-orbital overlap on charge carrier mobility, by precisely controlling only molecular arrangements without any chemical modifications. We synthesized disulfonic acid composed of a [1]benzothieno[3,2- b ][1]benzothiophene ( BTBT ) moiety, and prepared organic salts with four butylamine isomers. Regardless of the type of butylamine combined, electronic states of the constituent BTBT derivative were identical, and all BTBT arrangements were edge-to-face herringbone-type. However, depending on the difference of steric hindrance, center-to-center distances and dihedral angles between neighboring BTBT moieties slightly varied. Despite a similar arrangement, the photoconductivity of four organic salts differed by a factor of approximately two. Additionally, theoretical charge carrier mobilities from their crystal structures exhibited a strong correlation with their photoconductivity.
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