Thieno[3,2-b]thiophene (TT) and dithieno[3,2-b;3,2-d]thiophene (DTT) have drawn immense attention in the field of electronics and optoelectronics. In this work, the first examples of TTs (TPE2-TT and TPE3-TT) and a DTT (TPE2-DTT), having tetraphenylethylene (TPE) at the periphery exhibiting aggregation induced emission (AIE) in OLEDs, were designed and synthesized by the Suzuki coupling reaction. Their properties were investigated through experimental and computational studies, as well as X-ray diffraction and DFT optimization. TPE2-TT showed excellent device performance with a maximum luminance of 11 620 cd m⁻², a maximum current efficiency of 6.17 cd A⁻¹ and a maximum external quantum efficiency of 2.43%. Moreover, these synthetically easily accessible molecules have high thermal stability, which makes them perfectly suitable for optical applications.

Two novel D–A (donor–acceptor) and one D–A–D small molecules containing mesitylborane as an acceptor and triphenylamine as a donor, linked through a thieno[3,2-b]thiophene π-conjugated spacer, are synthesized and characterized. Their photo- and electrochemical properties were investigated by experimental and computational studies. The emission quantum efficiencies were determined to be between 46% and 68% in THF. Their solid-state quantum yields were recorded up to 42%. The fabricated electroluminescent devices as emitting materials showed sky-blue to yellowish green emissions. Their devices exhibit high performance with a turn-on voltage, maximal brightness, and highest luminescence efficiency of up to 4.0 V, 1200 cd m⁻² and 1.13 cd A⁻¹, respectively. These results pave new avenues for the future molecules possessing D and A units connected via fused thiophenes.