Panchromatic donor–acceptor–acceptor sensitizers based on 4H-cyclopenta[2,1-b:3,4-b′]dithiophen-4-one as a strong acceptor for dye-sensitized solar cells

Three new donor–acceptor–acceptor near-infrared organic dyes based on 4H-cyclopenta[2,1-b:3,4-b′]dithiophen-4-one as an additional acceptor were developed and used in dye-sensitized solar cells. By virtue of the simple donor–acceptor–acceptor configuration and systematic tuning of the electron-donating ability of the donor moiety, the absorption spectrum of HIQ3 on TiO2 extended to 900 nm. Remarkably, DSCs sensitized with HIQ3 showed broad incident monochromatic photon-to-current conversion efficiency spectra across the entire visible range and extending into the near-infrared region as far as 1100 nm.

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► Three new donor–acceptor–acceptor near-infrared organic dyes have been developed.
► All dyes demonstrated strong NIR absorption spectra.
►  The highest overall efficiency, 1.69%, was achieved among three dyes.
► Longest IPCE response wavelength reached to 1100 nm.