2,3-thienoimide-ended oligothiophenes as ambipolar semiconductors for multifunctional single-layer light-emitting transistors

The fascinating combination of light-emitting characteristics and electrical amplification identifies organic light-emitting transistors (OLETs) as key enabling devices for a wide variety of applications, ranging from displays to sensors. Pursuing a dual functionality in a single-layer architecture is either the major strength and the major challenge of this technology. Limitations mainly arise from the poor availability of organic semiconductors able to ensure good ambipolar behavior in charge transport together with an efficient light-emission in the solid state. In the present perspective, we report on the new class of thienoimide-ended oligothiophenes as molecular compounds simultaneously endowed with a good field-effect mobility for holes and electrons, good processability, self-assembly capability into nanostructures and remarkable properties of photo- and electroluminescence in solid state. The versatile chemical tuning of the molecular structure and the fine use of both solution-processed and physical deposition techniques in the realization of nanostructured thin-films are the major tools for controlling the packing of molecules and their intermolecular interactions at the solid state. Indeed, the inherent polymorphism of this class of compounds is directly correlated to their electrical and optoelectronic properties as active materials in multifunctional devices. Considering the field-effect transistor as a benchmark device platform, here we propose the extended family of thienoimide-ended oligothiophenes as a case study in virtue of i) the solid and throughout correlation of the molecular structure and solid-state organization with the figures of merit in transistor-based devices, and ii) the possibility of engineering highly-integrated planar organic optoelectronic devices with multiple functionalities for the investigation of photophysical and charge transport processes in organic compounds and, ultimately, the demonstration of real-setting applications of OLET technology.