Modification on C219 by coumarin donor toward efficient sensitizer for dye sensitized solar cells: A theoretical study

Dye sensitized solar cell sensitized by organic dye C219 (Chem. Mater, 2010, 22, 1915-1925) has reached the record efficiency (eta) of 10.1% with comparable short-circuit current density (J(sc)) but relatively lower open-circuit photovoltage (V-oc) as compared to that of ruthenium-based cells. With the motivation of further enhancing V-oc, we designed three dyes 1-3 with different electron donors, i.e. carbazole, indoline and coumarin. Based on the theoretical analysis of the conduction band energy shift of TiO2, electron injection rate and electron lifetime, the three designed dyes all show larger V-oc than that of C219. On the other hand, 3 should also have larger J(sc) compared with that of C219 due to its red-shifted spectrum and higher light harvesting efficiency. Thus we expect that the cell sensitized by 3 could exhibit both larger V-oc and J(sc) in comparison to the champion C219-based cells. (C) 2013 Elsevier Ltd. All rights reserved.