Synthesis and photovoltaic applications of a 4,4′- spirobi[cyclopenta[2,1-b;3,4-b′]dithiophene]-bridged donor/acceptor dye

A new donor/acceptor (D-A) spiro dye (SCPDT1) featuring two bithiophene units, connected through an sp³-hybridized carbon atom, was prepared by a multistep synthetic sequence involving the convenient assembly of the spiro system under mild catalytic conditions. The photocurrent spectrum of dye-sensitized solar cells incorporating SCPDT1 covers the spectral region ranging from 350 to 700 nm and reaches a wide maximum of ∼80% in the 420-560 nm range. Power conversion efficiencies of up to 6.02% were obtained.