New efficient organic dyes employing indeno[1,2-b]indole as the donor moiety for dye-sensitized solar cells

A new series of organic dyes based on indeno[1,2- b ]indole have been synthesized and applied in dye-sensitized solar cells (DSSCs) for the first time. These four dyes QX11 – 14 are constructed to a D–π–A type structure consisting of an indeno[1,2- b ]indole donor and a cyanoacrylic acid acceptor/anchoring group. Different π-bridges (thiophene and furan) and different alkyl groups (ethyl and hexyl) are involved to tune the photoelectric properties . Their optical, electrochemical, and photovoltaic properties, as well as the density functional theory calculations have been systematically investigated, indicating these four dyes are all capable as photosensitizers . The four dyes all show good DSSC performances and a highest power conversion efficiency up to 7.64% with a J sc of 15.8 mA cm −2 and a V oc of 763 mV has been achieved by the dye QX12 with a furan π-bridge and a pair of ethyl groups, which reaches 95% of the commercial N719 dye (8.07%) under AM 1.5G illumination. This result reveals indeno[1,2- b ]indole is a promising electron donor to construct efficient organic dyes for DSSCs.