Asymmetric liquid crystalline dibenzo[a,h]anthracenes for organic semiconductors with high mobility and thermal stability

Abstract

A series of asymmetric organic semiconductors based on N-shaped dibenzo[a,h]anthracene (DBA), Ph-DBA-Cn (n = 8, 10, 12), were developed. All Ph-DBA-Cn compounds had good chemical stability and smectic LC qualities, and thermally stable crystal phase can be maintained under 190 °C due to the suppressed molecular motions by the bent DBA core. High-quality crystalline films can be fabricated using a blade-coating technique. It was revealed that the average mobility of all Ph-DBA-Cn organic thin-film transistors (OTFTs) was estimated to be over 2.8 cm² V⁻¹ s⁻¹, and a Ph-DBA-C8 device in particular afforded exceptional mobility of up to 11.8 cm² V⁻¹ s⁻¹. The highly-ordered and uniaxially-oriented crystalline films composed of bilayer units were revealed to be responsible for their excellent electrical device performances. Furthermore, all Ph-DBA-Cn OTFTs can retain operational characteristics up to 160 °C over 1 cm² V⁻¹ s⁻¹. These findings will be crucial for the development of high-mobility and thermally durable OSCs for practical electronics.