Synthesis and optical and electrochemical properties of a phenanthrodithiophene (fused-bibenzo[c]thiophene) derivative

Abstract

We designed and developed a fused-bibenzo[c]thiophene, namely, 2,9-bis(tert-butyldimethylsilyl)phenanthro[9,8-bc:10,1-b′c′]dithiophene (PHDT-Si), as a new π-building block in the emitters, photosensitizers and semiconductors for organic optoelectronic devices. Based on photophysical (photoabsorption, fluorescence and time-resolved fluorescence spectroscopy) and electrochemical measurements (cyclic voltammetry), and density functional theory (DFT) calculations, this work reveals that the fused-bibenzo[c]thiophene PHDT-Si, which is prepared by an efficient synthesis method, has a rigid, high planar and expanded π-conjugation structure, and possesses intense photoabsorption and fluorescence properties (λ^abs_max = 598 nm (ε_max = 41 000 M⁻¹ cm⁻¹) and λ^fl_max = 613 nm (Φ_f = 0.74) in toluene) in the long-wavelength region and undergoes an electrochemically reversible oxidation process, compared to non-fused 1,1′-bis(tert-butyldimethylsilyl)-4,4′-bibenzo[c]thiophene (BBT-Si).