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 p-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.