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Electrochemical Self-assembly of Hierarchical Dendritic Bi2Se3Nanostructures and Corresponding Photoelectric Conversion Properties

Author: HanCan
Tutor: LiuYeXiang
School: Central South University
Course: Metallurgical Engineering
Keywords: Bismuth selenide （Bi2Se3） dendritic nanostructures electrochemical self-assembly
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Type: Master's thesis
Year: 2013
Downloads: 6
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Abstract


Abstract:Based on quantum size effect and dielectric confinement effect, nanostructured V2-VI3group materials have presented peculiar properties in optics, thermotics, and magnetics, and found broad application potential in photoelectric and thermoelectric devices, and infrared spectroscopy, etc. Among various preparation approaches, electrochemical self-assembly technique has the advantage of low-cost, high-efficiency and suitable for large-area production. With taking bismuth selenide (Bi2Se3) as the object of study, we report here the reasearch work on the electrochemical self-assembly route of hierarchical dendritic Bi2Se3nanostructures and, corresponding photoelectric conversion properties. The main conclusions obtained are listed as following:(1) Well-defined hierarchical dendritic Bi2Se3nanostructures have been synthesized via electrochemical self-assembly approach. The electrochemical reactions in the Bi-Se electrolyte solution were studied by cyclic voltammetry, and effects of deposition potential, deposition tempreture, addition of complex (KSCN) and deposition time on the film morphology and composition were also investigated. A possible mechanism for the formation of the dendritic structures was concluded. Besides, the optimal synthesis conditions were taken at the deposition potential of-0.15V, the deposition tempreture of25℃, addition of KSCN with10mmol/L, and the deposition time of60min.(2) Systematic characterization and analysis of the prepared hierarchical dendritic Bi2Se3nanostructures have been conducted. According to the SEM, EDS, TEM, XRD, XPS and Raman results, the prepared sample follows a rhombohedral hexagonal Bi2Se3crystal structure (JCPDS33-0214), and some of the atoms on surface of the sample were easily oxidized. The Bi2Se3nanostructures showed a larger band gap of0.50±0.01eV than that of common Bi2Se3film, which was obtained from UV-VIS-NIR analysis. Additionally, PEC and Motto-Schottky tests were employed to characterize the electrical and photoelectrochemical properties. These results illustrate that both the Bi2Se3nanostructures and common Bi2Se3film show a p-type bulk conductivity and a n-type surface conductivity, with the flat band potential of-0.03V and-0.07V, the carrier concentration of2.9x1020%cm3and2.1><1020/cm3, respectivly. Moreover, the Bi2Se3nanostructures have a better photovoltaic conversion performance than common Bi2Se3film.

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