title: Tuning band alignment by CdS layers using a SILAR method to enhance TiO2/CdS/CdSe quantum-dot solar-cell performance.
abstract: We report tuning band alignment by optimized CdS layers using a SILAR method to achieve the recorded best performance with about 6% PCE in TiO2/CdS/CdSe QDSSCs. Combining experimental and theoretical studies, we find that a better lattices match between CdS and TiO2 assists the growth of CdSe, and the combined effect of charge transfer and surface dipole moment at the TiO2/CdS/CdSe interface shifts the energy levels of TiO2 upward and increases Voc of the solar cells. More importantly, the band gap of CdS buffer layers is sensitive to the distortion induced by lattice mismatch and numbers of CdS layers. For example, the barrier for charge transfer disappears when there are more than 4 layers of CdS, facilitating the charge injection from CdSe to TiO2.
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China. panfeng@pkusz.edu.cn.
authors.forename: Bingkai
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China. panfeng@pkusz.edu.cn.
authors.forename: Jiaxin
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. linyuan@iccas.ac.cn.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. linyuan@iccas.ac.cn.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Fang
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China. panfeng@pkusz.edu.cn and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Lin-Wang
authors.initials: LW
authors.lastname: Wang
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China. panfeng@pkusz.edu.cn and Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. linyuan@iccas.ac.cn.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lin
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China. panfeng@pkusz.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Pan