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-pi-A type structure consisting of an indeno[1,2-b]indole donor and a cyanoacrylic acid acceptor/anchoring group. Different pi-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 Vac of 763 mV has been achieved by the dye QX12 with a furan pi-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. (C) 2016 Elsevier B.V. All rights reserved.