Investigating the Thermal Stability of Organic Thin‐Film Transistors and Phototransistors Based on [1]‐Benzothieno‐[3,2‐ b ]‐[1]‐benzothiophene Dimeric Derivatives

Two new highly thermally stable [1]benzothieno[3,2‐ b ][1]benzothiophene (BTBT) dimeric derivatives, namely 1,4‐bis([1]benzothieno[3,2‐ b ][1]benzothiophene‐2‐yl)benzene (BTBT‐Ph‐BTBT) and 4,4′‐bis([1]benzothieno[3,2‐ b ][1]benzothiophene‐2‐yl)‐1,1′‐biphenyl (BTBT‐DPh‐BTBT), were synthesized by combining two simple fragment structures. Compared to the monomer compound 2‐phenyl[1]benzothieno[3,2‐ b ][1]benzothiophene (Ph‐BTBT, μ max =3.4×10 −2  cm 2  V −1  s −1 ), the organic thin‐film transistors (OTFTs) based on BTBT‐Ph‐BTBT and BTBT‐DPh‐BTBT showed significantly higher mobility (up to 2.5 and 3.6 cm 2  V −1  s −1 for BTBT‐Ph‐BTBT and BTBT‐DPh‐BTBT, respectively). The mobility of OTFTs based on BTBT‐Ph‐BTBT was kept at a high value (2.4×10 −1  cm 2  V −1  s −1 ) after the devices were thermally annealed at 350 °C. Furthermore, the organic phototransistors (OPTs) based on BTBT‐Ph‐BTBT and BTBT‐DPh‐BTBT displayed high photosensitivities in a range of 250–400 nm with a low intensity, making these materials potentially applicable for sensitive optoelectronic devices.