title: Co-sensitization promoted light harvesting with a new mixed-addenda polyoxometalate [Cu(C12H8N2)2]2[V2W4O19]·4H2O in dye-sensitized solar cells.
abstract: A di-vanadium-substituted Lindqvist-type polyoxometalate [Cu(C12H8N2)2]2[V2W4O19]·4H2O (1) was hydrothermally synthesized and characterized structurally by single crystal X-ray diffraction analysis. X-ray photoelectron spectroscopy and energy disperse spectroscopy tests further prove the existence of vanadium. Ultraviolet photoelectron spectroscopy and density functional theoretical studies indicate that the energy level of 1 matches well with the conduction band of the TiO2. Furthermore, considering the semiconductor-like nature of 1 and the introduction of transition metal element Cu synchronously extends the absorption to the visible region, which should also be beneficial to the photovoltaic device performance. 1-Doped TiO2 composites (denoted as 1@TiO2) have been successfully fabricated by a simple sol-gel method, and introduced into the dye-sensitized solar cells (DSSCs) as co-sensitizers in N719-sensitized photoanodes by mixing 1@TiO2 with P25 nanoparticles with different weight ratios to enhance the photoelectric conversion efficiency. The investigations show that the DSSC assembled with 1@TiO2/19P25 photoanode has the best performance and the overall improvement of the efficiency is 21.6% compared with pure P25. Furthermore, the electrochemical impedance spectroscopy and open-circuit voltage decay investigations show that the cosensitization of 1 and N719 can promote electron transfer and restrain charge recombinations in the DSSCs, resulting in a longer electron lifetime.
authors.affiliation: Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. China. chenwl@nenu.edu.cn wangeb889@nenu.edu.cn wangeb889@hotmail.com.
authors.forename: Sha-Sha
authors.initials: SS
authors.lastname: Xu
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Chen
authors.forename: Yan-Hua
authors.initials: YH
authors.lastname: Wang
authors.forename: Yang-Guang
authors.initials: YG
authors.lastname: Li
authors.forename: Zhu-Jun
authors.initials: ZJ
authors.lastname: Liu
authors.forename: Chun-Hui
authors.initials: CH
authors.lastname: Shan
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Su
authors.forename: En-Bo
authors.initials: EB
authors.lastname: Wang