A Low-Energy-Gap Organic Dye for High-Performance Small-Molecule Organic Solar Cells

A novel donor–acceptor–acceptor (D–A–A) donor molecule, <b>DTDCTB</b>, in which an electron-donating ditolylaminothienyl moiety and an electron-withdrawing dicyanovinylene moiety are bridged by another electron-accepting 2,1,3-benzothiadiazole block, has been synthesized and characterized. A vacuum-deposited organic solar cell employing <b>DTDCTB</b> combined with the electron acceptor C<sub>70</sub> achieved a record-high power conversion efficiency (PCE) of 5.81%. The respectable PCE is attributed to the solar spectral response extending to the near-IR region and the ultracompact absorption dipole stacking of the <b>DTDCTB</b> thin film.