Band gap engineering in PbS nanostructured thin films from near-infrared down to visible range by in situ Cd-doping
TL;DR: In this paper, the modification of optical band gap of PbS nanostructured films over a wide spectral range (∼475-1000nm) due to in situ Cd-doping and size confinement was reported.
About: This article is published in Journal of Alloys and Compounds.The article was published on 2010-04-09. It has received 71 citations till now. The article focuses on the topics: Band gap & Chemical bath deposition.
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TL;DR: In this article, thin films of ZnSe were deposited on soda lime glass substrates by thermal evaporation and annealed in vacuum at various temperatures in the range of 100-300°C. Structural and optoelectronic properties of these films were investigated and compared with the available data.
119 citations
TL;DR: The systematic study of PbS-sensitized solar cells utilizing different metal oxide semiconductors as electron transporters would provide useful insights and promote the development of semiconductor-s Sensitized mesoscopic solar cells employing panchromatic sensitizers.
Abstract: Metal oxide semiconductors with lower lying conduction band minimum and superior electron mobility are essential for efficient charge separation and collection in PbS-sensitized solar cells. In the present study, mesoscopic SnO2 was investigated as an alternative photoanode to the commonly used TiO2 and examined comprehensively in PbS-sensitized liquid junction solar cells. To exploit the capability of PbS in an optimized structure, cascaded nPbS/nCdS and alternate n(PbS/CdS) layers deposited by a successive ionic layer adsorption and reaction method were systematically scrutinized. It was observed that the surface of SnO2 has greater affinity to the growth of PbS compared with TiO2, giving rise to much enhanced light absorption. In addition, the deposition of a CdS buffer layer and a ZnS passivation layer before and after a PbS layer was found to be beneficial for efficient charge separation. Under optimized conditions, cascaded PbS/CdS-sensitized SnO2 exhibited an unprecedented photocurrent density of 17.38 mA cm−2 with pronounced infrared light harvesting extending beyond 1100 nm, and a power conversion efficiency of 2.23% under AM 1.5, 1 sun illumination. In comparison, TiO2 cells fabricated under similar conditions showed much inferior performance owing to the less efficient light harnessing of long wavelength photons. We anticipate that the systematic study of PbS-sensitized solar cells utilizing different metal oxide semiconductors as electron transporters would provide useful insights and promote the development of semiconductor-sensitized mesoscopic solar cells employing panchromatic sensitizers.
58 citations
TL;DR: In this article, Nanocrystalline undoped and Cr-doped PbS thin films were prepared on glass substrates by a simple chemical bath deposition method and X-ray diffraction analyses of the films showed their polycrystalline nature with cubic structure and preferential growth along the (111) orientation.
Abstract: Nanocrystalline undoped and Cr-doped PbS thin films were prepared on glass substrates by a simple chemical bath deposition method. The X-ray diffraction analyses of the films showed their polycrystalline nature with cubic structure and preferential growth along the (111) orientation. Cr incorporation decreases the average PbS crystallite size from 59.97 to 37.59 nm, whereas the strain and dislocation density showed an increasing trend. The atomic ratio of doping for Cr is about 0.63, 1.75, and 4.70% according to energy-dispersive X-ray (EDX) spectroscopy. Morphological analysis showed that the average sizes of nanoclusters decreased from 73 to 41 nm as the Cr concentration increased. The optical band gap values are increased with increasing Cr doping. The photoelectrochemical (PEC) behaviors and the stability of the Cr doped PbS photoelectrodes were studied in 0.3 M Na2SO3 electrolyte solution. Also, the incident photon-to-current efficiency and applied bias photon-to-current efficiency are calculated and showed optimized values of 13.5% and 1.44% at 0.68 V and 390 nm. Moreover, the optimized electrode shows high chemical stability and a long lifetime. Finally, the effect of temperature on the PEC behaviors is evaluated and the different thermodynamic parameters are calculated.
58 citations
TL;DR: In this article, undoped and Strontium-doped lead sulfide (PbS) thin films were deposited on glass substrates by chemical bath deposition (CBD) technique.
55 citations
TL;DR: In this paper, the synthesis of pure and Bi-doped PbS (Bi:PbS) nanopowders was attained facilely by the chemical route at low temperature.
46 citations
References
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TL;DR: Sittingizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers, and makes use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
Abstract: In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage1. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300–1,600 nm), thermal imaging (1,500 nm and beyond), biological imaging (transparent tissue windows at 800 nm and 1,100 nm), thermal photovoltaics (>1,900 nm), and solar cells (800–2,000 nm). Photoconductive polymer devices have yet to demonstrate sensitivity beyond ∼800 nm (refs 2,3). Sensitizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) into the infrared. We achieve, in a solution-processed device and with sensitivity far beyond 800 nm, harvesting of infrared-photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
1,860 citations
TL;DR: In this paper, a planar Schottky photovoltaic device was constructed from solution-processed PbS nanocrystal quantum dot films with aluminum and indium tin oxide contacts.
Abstract: Planar Schottky photovoltaic devices were prepared from solution-processed PbS nanocrystal quantum dot films with aluminum and indium tin oxide contacts. These devices exhibited up to 4.2% infrared power conversion efficiency, which is a threefold improvement over previous results. Solar power conversion efficiency reached 1.8%. The simple, optimized architecture allows for direct implementation in multijunction photovoltaic device configurations.
267 citations
TL;DR: Novel star-shaped PbS dendrites with six symmetric arms along the 100 direction have been achieved using Pb(AC)2 and thioacetamide (TAA) as precursors, and this approach is expected to be employed for the control-shaped synthesis of other fcc structural semiconductor nanomaterials.
Abstract: Well-defined single-crystalline PbS nano- and microstructures including dendrites, multipods, truncated nanocubes, and nanocubes were synthesized in high yield by a simple solution route. Novel star-shaped PbS dendrites with six symmetric arms along the 〈100〉 direction, each of which shows one trunk (long axis) and four branches (short axes), have been achieved using Pb(AC)2 and thioacetamide (TAA) as precursors, under the molar ratio Pb(AC)2/TAA = 2/1, at initial reaction temperature 80 °C, refluxing for 30 min at 100 °C, in the presence of cetyltrimethylammonium bromine (CTAB). The “nanorods” in each branch are parallel to each other in the same plane and are perpendicular to the trunk. The truncated nanocubes mainly bounded by the {100} plane were prepared under a different Pb(AC)2/TAA molar ratio, at initial reaction temperature 40 °C, refluxing for 12 h at 100 °C. Based on the systematic studies on their shape evolution, a possible growth mechanism of these PbS nano- and microstructures was proposed....
178 citations
TL;DR: Structural characterization indicates that shells of the hollow spheres are composed of PbS nanoparticles with diameters of about 12 nm, and uniform silica layers were successfully coated onto the hollow sphere via a modified Stöber method to enhance their performance for promising applications.
Abstract: PbS hollow nanospheres with diameters of 80-250 nm have been synthesized by a surfactant-assisted sonochemical route. The nanostructures were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), (high-resolution) transmission electron microscopy [(HR)TEM], and scanning electron microscopy (SEM) images. Structural characterization indicates that shells of the hollow spheres are composed of PbS nanoparticles with diameters of about 12 nm. The formation of the hollow nanostructure was explained by a vesicle-template mechanism, in which sonication and surfactant play important roles. Furthermore, uniform silica layers were successfully coated onto the hollow spheres via a modified Stober method to enhance their performance for promising applications.
158 citations
TL;DR: Oleic acid (OA) capped PbS nanoparticles were chemically synthesized and characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray electron diffraction (XRD) and X-Ray photoelectron spectroscope (XPS) as discussed by the authors.
117 citations