Synthesis, characterization and OFET performance of A–D–A semiconducting small molecules functionalized with perylene diimide groups

Abstract

Organic semiconductor molecules have been utilized in commercial applications owing to their outstanding advantages, such as tunable absorption spectra and electronic energy levels, and superior thermal stability. Three perylene diimide (PDI)-based small molecules have been synthesized and their chemical–physical, electrochemical and organic field effect transistor (OFET) properties have been characterized. Three different central IDT electron donor cores symmetrically functionalized with PDI electron-acceptor moieties and flanked in the terminal positions with alkyl groups were purposely designed. All the molecules consist of a PDI group as the acceptor (A) unit and indacenodithiophene (IDT) as the donor (D) unit. The impact of the acceptor–donor–acceptor (A–D–A) structures on the photoelectric performance of the molecules was investigated. The conjugated molecules exhibit full coverage absorption in the visible light spectrum, implying that they could be utilized for more potential applications in optoelectronic devices. All the molecules exhibited good thermal stability and typical n-type semiconductor behavior with a highest electron mobility of up to 2.09 × 10⁻¹ cm² V⁻¹ s⁻¹ when I_on/I_off = 10⁴. S-PDI-IDT-2 exhibited ambipolar transport properties, with a hole transportation mobility on the order of 10⁻³.