Selenium-Containing Fused Bicyclic Heterocycle Diselenolodiselenole: Field Effect Transistor Study and Structure-Property Relationship

The first application of the diselenolodiselenole (C₄Se₄) heterocycle as an active organic field effect transistor materials is demonstrated here. C₄Se₄ derivatives (2a-2d) were obtained by using a newly developed straightforward diselenocyclization protocol, which includes the reaction of diynes with selenium powder at elevated temperature. C₄Se₄ derivatives exhibit strong donor characteristics and planar structure (except 2d). The atomic force microscopic analysis and thin-film X-ray diffraction pattern of compounds 2a-2d indicated the formation of distinct crystalline films that contain large domains. A scanning electron microscopy study of compound 2b showed development of symmetrical grains with an average diameter of 150 nm. Interestingly, 2b exhibited superior hole mobility, approaching 0.027 cm² V^-1 s^-1 with a transconductance of 9.2 μS. This study correlate the effect of stacking, Se···Se intermolecular interaction, and planarity with the charge transport properties and performance in the field effect transistor devices. We have shown that the planarity in C₄Se₄ derivatives was achieved by varying the end groups attached to the C₄Se₄ core. In turn, optoelectronic properties can also be tuned for all these derivatives by end-group variation.