Investigating the impact of substitution on the optoelectronic properties of benzothiophenone S,S-dioxide

A series of dyes has been synthesized from 3,5,6-tribromobenzothiophene S,S-dioxide over 3 to 5 steps, leveraging a key intermediate: 5,6-dibromobenzo[b]thiophene-3(2H)-one S,S-dioxide. This intermediate serves as a highly versatile platform due to its unique functional groups: the bromines facilitate organometallic couplings, the ketone undergoes condensations, and the methylene group positioned between the ketone and sulfone enables the introduction of conjugated systems. The synthesis follows a consistent sequence of steps, ultimately yielding dyes with absorbance in the infrared (IR) region. By tuning the donor and acceptor groups, the resulting compounds can act as either electron donors or acceptors in solar cell applications, with LUMO energy levels observed around −4 eV.