Bithiazole Dicarboxylate Ester: An Easily Accessible Electron-Deficient Building Unit for π-Conjugated Polymers Enabling Electron Transport

Thiazole has been less focused, compared to thiophene, as the building unit for pi-conjugated polymers that are used in organic electronic devices despite its electron deficiency and ability to coplanarize the polymer backbone, which are crucial for design of such pi-conjugated polymers. Here, we show that bithiazole dicarboxylate ester (BETz), which is quite easily synthesized, is a promising building unit for pi-conjugated polymers. Copolymers based on BETz, having unsubstituted bithiophene and bithiazole as counits, indeed form highly crystalline structures in thin films, which is beneficial for semiconducting properties. Of particular interest is that the BETz-based polymers are found to show electron-transport property even though the lowest unoccupied molecular orbital (LUMO) energy levels are not very low, as they show ambipolar and unipolar n-channel behaviors depending on the counit in organic transistor devices. We believe that BETz allows us to design a wide variety of pi-conjugated polymers that provide fascinating functions in organic electronic devices.

Automated summary

Studies have shown that bithiazole dicarboxylate ester (BETz) is a promising building unit for pi-conjugated polymers, with copolymers forming highly crystalline structures in thin films, which is beneficial for semiconducting properties.