title: Engineering the interfaces of ITO@Cu2S nanowire arrays toward efficient and stable counter electrodes for quantum-dot-sensitized solar cells.
abstract: Among the issues that restrict the power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSSCs), insufficient catalytic activity and stability of counter electrodes (CEs) are critical but challenging ones. The state-of-the-art Cu/Cu2S CEs still suffer from mechanical instability and uncertainty due to the reaction of copper and electrolyte. Herein, ITO@Cu2S core-shell nanowire arrays were developed to fabricate CEs for QDSSCs, which have no such issues in Cu/Cu2S CEs. These nanowire arrays exhibited small charge transfer resistance and sheet resistance, and provided more active catalytic sites and easy accessibility for electrolyte due to the three-dimensional structure upon use as CEs. More interestingly, it was found that the interface of ITO/Cu2S significantly affected the performance of ITO@Cu2S nanowire array CEs. By varying synthetic methods, a series of ITO@Cu2S nanowire arrays were prepared to investigate the influence of ITO/Cu2S interface on their performance. The results showed that ITO@Cu2S nanowire array CEs with a continuous Cu2S nanocrystal shell fabricated via an improved cation exchange route exhibited excellent and thickness-dependent performance. The PCE of corresponding QDSSCs increased by 11.6 and 16.5% compared to that with the discrete Cu2S nanocrystal and the classic Cu/Cu2S CE, respectively, indicating its promising potential as a new type of CE for QDSSCs.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Science ,2 North 1st Street, Zhongguancun, Beijing 100190, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.forename: Qian-Qing
authors.initials: QQ
authors.lastname: Ge
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Yu
authors.forename: Yu-Gang
authors.initials: YG
authors.lastname: Zou
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Jiang
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Hu
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Song
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Wan
keywords: counter electrodes; interface; nanowires; quantum dots; solar cells