Organic Photosensitizers Incorporating Rigid Benzo[1,2-b:6,5-b']dithiophene Segment for High-Performance Dye-Sensitized Solar Cells.

Benzo[1,2-b:6,5-b']dithiophene (BDT) entity with rigid skeleton is introduced into the conjugated spacer of organic dyes, with triphenylamine as the electron donor and 2-cyanoacrylic acid as the acceptor, have been prepared for dye-sensitized solar cells. Inserting an aromatic entity between BDT and the anchor extends the absorption wavelength of the dyes and improves the dark current suppression efficiency, and consequently leads to better cell performance. Addition of chenodeoxycholic acid coadsorbent alleviates dye aggregation and results in better cell efficiency. The dye inserted with 4H-cyclopenta[2,1-b:3,4-b']dithiophene entity achieves the best efficiency (9.11%) when I- /I3 - was used as the electrolyte. When Co(phen)3 2+/3+ was used as the electrolyte, the efficiency further boosts to 9.88%.