Design of high‐performance chlorine type dyes for dye‐sensitized solar cells

Intrinsic defect of electronic structure for the chlorine‐type porphyrin 1, which was synthesized for use in dye‐sensitized solar cell (DSSC), is found by theoretical calculation including density functional method (DFT), time‐dependent DFT, and C+/C? function. It is believed that the limited cell performance obtained by using dye 1 as the sensitizer is due to the existence of this electronic defect. To avoid this defect, a series of novel molecules with electron deficient π bridge were designed. The subsequent theoretical calculation indicated that the electron deficient π bridge in the newly designed molecule is quite effective in offsetting the electronic defect observed for dye 1. The parameters for the designed molecules closely associated with open‐circuit voltage and short‐circuit current density including dipole moment of dye vertical to the surface of semiconductor and light‐harvesting efficiency were then evaluated. By comparing these parameters of designed dyes with those of dye 1, we can predict that the DSSC based on dye 4 (2, 6‐cyan benzoic acid as anchoring group) should possess enhanced performance, which would be a valuable theoretical guidance for the practical work. © 2013 Wiley Periodicals, Inc.