Nanostructured Chalcogenides
Nanoscale materials are currently being exploited as active components in a wide range of technological applications such as composite materials, chemical sensing, biomedicine, optoelectronics, and nanoelectronics. The term nano- refers to material struct
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Nanostructured Chalcogenides Mandeep Singh Bakshi and Gurinder Kaur Ahluwalia
M.S. Bakshi, Ph.D. (*) Department of Natural and Applied Sciences, University of Wisconsin - Green Bay, 2420 Nicolet Drive, Green Bay, WI 54311-7001, USA e-mail: [email protected] G.K. Ahluwalia, Ph.D Materials and Nanotechnology Research Laboratory, Department of Physics College of The North Atlantic, Labrador West Campus, 1600 Nichols Adam Highway, Labrador City, A2V 0B8, NL, Canada e-mail: [email protected] © Springer International Publishing Switzerland 2017 G.K. Ahluwalia (ed.), Applications of Chalcogenides: S, Se, and Te, DOI 10.1007/978-3-319-41190-3_3
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M.S. Bakshi and G.K. Ahluwalia
Introduction
Nanostructuring of chalcogenides is one of the most promising areas of materials science which finds inherent applications from electronic devices to biomarkers for cancer cells detection Colloidal quantum dots (QDs) were first investigated by L. E. Brus et al. [1] in 1983 and have attracted much attention as color saturated, highly luminescent, and robust lumophors, due to their unique optical properties, such as facile bandgap tunability, wide absorption range, spectral purity, and photostability/ chemical stability. Among various colloidal QDs based on II–VI (i.e., cadmium sulfide (CdS) [2], cadmium selenide (CdSe) [3–7], cadmium telluride (CdTe) [8, 9], zinc selenide (ZnSe) [10], or zinc oxide (ZnO) [11]), III–V (i.e., indium arsenide (InAs) [12] and indium phosphide (InP) [13]), IV–VI (i.e., lead selenide (PbSe) [14, 15] and lead sulfide (PbS) [16–20]), and IV(i.e., Si [21–24]) compounds, II–VI QDs comprising cadmium and zinc chalcogenides have shown considerable progress in terms of high color purity (full width at half maximum: 20–40 nm) and photoluminescence quantum efficiency (PL QE, above 70 %) in the visible range. Such a success in materials science harnessed the development of colloidal QD-based light-emitting diodes (QD-LEDs) aiming toward economic, stable, and high performance next-generation devices, which will potentially replace conventional inorganic or organic based-LEDs. From a technological perspective, lead chalcogenide quantum dots (QDs) are of interest because they are among the few materials that can provide tunable electronic transitions at important near-infrared (NIR) wavelengths. PbSe is a convenient choice for inorganic semiconductor QDs for NIR applications (λ > 1 μm) as the colloidal synthesis is reproducible and yields nanocrystals with narrow size distributions. In addition the large exciton Bohr radius of 46 nm leads to a strong confinement of QD excitons throughout the synthetically accessible range of 2–10 nm (corresponding to absorption peaks λ ¼ 1 μm (1.2 eV) to λ > 2.4 μm (
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