Article

Tuning the shape and thermoelectric property of PbTe nanocrystals by bismuth doping.

Department of Chemistry, National University of Singapore, Singapore.
Nanoscale (Impact Factor: 6.73). 07/2010; 2(7):1256-9. DOI: 10.1039/c0nr00115e
Source: PubMed

ABSTRACT We report the synthesis of a series of monodispersed Bi-doped PbTe nanocrystals with tunable morphologies by using a doping precursor of bismuth(III) 2-ethylhexanoate. The as-synthesized Pb(1-x)Bi(x)Te (x = 0.005, 0.010, 0.015, 0.020) nanocrystals are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Hall measurements. The nanocrystals with controlled spherical, cuboctahedral, and cubic shapes were readily prepared by varying the Bi doping concentration. Thermoelectric investigation of these nanocrystals shows that the Bi(3+) doping increases electrical conductivity from 350 to 650 K and changes the Seebeck coefficient sign from positive to negative.

0 Bookmarks
 · 
81 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The chemistry, material processing and fundamental understanding of colloidal semiconductor nanocrystals (quantum dots) are advancing at an astounding rate, bringing the prospects of widespread commercialization of these novel and exciting materials ever closer. Interest in narrow bandgap nanocrystals in particular has intensified in recent years, and the results of research worldwide point to the realistic prospects of applications for these materials in solar cells, infrared optoelectronics (e.g. lasers, optical modulators, photodetectors and photoimaging devices), low cost/large format microelectronics, and in biological imaging and biosensor systems to name only some technologies. Improvements in fundamental understanding and material quality are built on a vast body of experience spread over many different methods of colloidal synthetic growth, each with their own strengths and weaknesses for different materials and sometimes with regard to particular applications. The nanocrystal growth expertise is matched by a rapidly expanding, and highly interdisciplinary, understanding of how best to assemble these materials into films or hybrid composites and thereby into useful devices, and again there are many different strategies that can be adopted. In this review we have attempted to survey and compare the recent work on colloidal synthesis, film and nanocrystal composite material fabrication, concentrating on narrow bandgap chalcogenide materials and some of their topical applications in the solar energy and biological fields. Since these applications are attracting rising interest across a wide range of disciplines, from the biological sciences, device engineering, and materials processing fields as well as the physics and synthetic chemistry communities, we have endeavoured to make the review of these narrow bandgap nanomaterials both comprehensive and accessible to newcomers to the area.
    Chemical Society Reviews 01/2013; · 24.89 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of <5 × 10(-6)Ω m. It is demonstrated that Ag(2)Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag(2)Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.
    Nanoscale 06/2012; 4(13):3926-31. · 6.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bandgap engineering and shape control are important and advantageous for potential applications involving colloidal ZnO nanocrystals. Here we demonstrate the syntheses of high quality alloyed CdxZn1-xO nanocrystals with well-defined shapes, from faceted particles to tetrapods and ultrathin nanowires. By comparing the optical bandgaps of the pure ZnO, CdxZn1-xO and MgxZn1-xO nanocrystals with various dimensions, we conclude that bandgap engineering of colloidal ZnO nanocrystals via cadmium alloying effectively narrows the bandgaps. Our study may shed light on the design and syntheses of colloidal alloyed oxide nanocrystals with controlled band structures and shapes.
    Nanoscale 06/2013; · 6.73 Impact Factor