title: Multilayer Dye Aggregation at Dye/TiO2Interface via π…π Stacking and Hydrogen Bond and Its Impact on Solar Cell Performance: A DFT Analysis.
abstract: Multilayer dye aggregation at the dye/TiO2interface of dye-sensitized solar cells is probed via first principles calculations, using p-methyl red azo dye as an example. Our calculations suggest that the multilayer dye aggregates at the TiO2surface can be stabilized by π…π stacking and hydrogen bond interactions. Compared with previous two-dimensional monolayer dye/TiO2model, the multilayer dye aggregation model proposed in this study constructs a three-dimensional multilayer dye/TiO2interfacial structure, and provides a better agreement between experimental and computational results in dye coverage and dye adsorption energy. In particular, a dimer forms by π…π stacking interactions between two neighboring azo molecules, while one of them chemisorbs on the TiO2surface; a trimer may form by introducing one additional azo molecule on the dimer through a hydrogen bond between two carboxylic acid groups. Different forms of multilayer dye aggregates, either stabilized by π…π stacking or hydrogen bond, exhibit varied optical absorption spectra and electronic properties. Such variations could have a critical impact on the performance of dye sensitized solar cells.
authors: Department of Applied Physics, School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, No. 219 Ning Liu Road, Nanjing 210044, China.
authors: Lei
authors: L
authors: Zhang
authors: Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 Create Way, 138602, Singapore.
authors: Xiaogang
authors: X
authors: Liu
authors: Department of Materials Physics, School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors: Weifeng
authors: W
authors: Rao
authors: Department of Applied Physics, School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, No. 219 Ning Liu Road, Nanjing 210044, China.
authors: Jingfa
authors: J
authors: Li