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 π-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.