Organic Dyes Incorporating the Dithieno[3,2-f:2′,3′-h]quinoxaline Moiety for Dye-Sensitized Solar Cells

New donor–acceptor′–acceptor‐type sensitizers (QBT dyes), comprising arylamine as the electron donor, dithieno[3,2‐f:2′,3′‐h]quinoxaline as the internal acceptor, and 2‐cyanoacrylic acid as both the acceptor and anchor, have been synthesized. The QBT dyes have broad absorption spectra covering the range of λ=368–487 nm with a highest molar extinction coefficient of up to approximately 40 000 M−1 cm−1. The light‐to‐electricity conversion efficiencies of the dye‐sensitized solar cells (DSSCs) fabricated from the dyes range from 6.11 to 7.59 % under simulated AM 1.5 G illumination. Upon addition of a threefold concentration of chenodeoxycholic acid as the co‐adsorbent, the best performance cell has a power‐conversion efficiency of 8.41 %, which is higher than that of the N719‐based standard DSSC (8.27 %). More acceptance: New donor–acceptor′–acceptor‐type sensitizers with a rigid dithieno[3,2‐f:2′,3′‐h]quinoxaline segment comprised of electron‐rich and electron‐deficient units in the conjugated spacer are proposed for dye‐sensitized solar cells. Their structure gives rise to broad absorption spectra and high molar extinction coefficient, resulting in power conversion efficiencies higher than that of the N719 dye.