title: Cyano or o-nitrophenyl? Which is the optimal electron-withdrawing group for the acrylic acid acceptor of D-π-A sensitizers in DSSCs? A density functional evaluation.
abstract: We report a DFT, TDDFT and DFTB investigation of the performance of two donor-π-acceptor (D-π-A)-type organic dyes bearing different electron-withdrawing groups (EWG) for dye-sensitized solar cells (DSSCs) to evaluate which EWG is better for an acrylic acid acceptor, i.e., Cyano (-CN) or o-nitrophenyl (o-NO2-Ph). A series of theoretical criteria applied successfully in our previous work to explain the different performance of organic dyes related to open-circuit photovoltage (Voc) and short-circuit current density (Jsc) were used to evaluate the performance of the dyes with just different EWG. Our calculated results reveal that dye 2 with o-NO2-Ph has a larger vertical dipole moment, more electrons transferred from the dye to the semiconductor and a lower degree of charge recombination, which could lead to larger Voc; while the larger driving force and comparable light harvesting efficiency could lead to higher J sc , highlighting the potential of o-NO2-Ph as an EWG in an acrylic acid acceptor.
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Chang Chun 130024, Jilin, People's Republic of China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
authors.forename: Yu-He
authors.initials: YH
authors.lastname: Kan
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Geng
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
authors.forename: Yu-Ai
authors.initials: YA
authors.lastname: Duan
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Su