Modulation of photovoltaic behavior of dye-sensitized solar cells by electron donors of porphyrin dyes and cosensitization

Porphyrin dyes have received great attention due to their excellent photovoltaic performance in dye-sensitized solar cells (DSSCs). In this work, dyes XC1-XC3 were synthesized by introducing various numbers of bis(4-methoxyphenyl)amino and p-hexyloxyphenyl groups to porphyrin mesa-positions. The XC1 molecule contains two p-hexyloxyphenyl groups, and its DSSCs showed the power conversion efficiency of 4.81%. For XC2 and XC3, the replacement of p-hexyloxyphenyl with diphenylamino groups can effectively enhance the light harvesting around 500 nm. However, the highest occupied molecular orbitals (HOMOs) were elevated too much, which suppressed the dye regeneration processes, leading to low cell efficiencies of 2.51% and 1.27% for XC2, and XC3, respectively. To further improve the cell performance, an anthracene derivative C1 was used as the cosensitizer for XC1, which increased both the J(sc) and V-oc values, with an improved efficiency of 5.75%. (C) 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.