New routes to sustainable photovoltaics: evaluation of Cu2ZnSnS4 as an alternative absorber material. Phys Status Solidi B-Basic Solid State Phys

Present address: Laboratoire Photovoltaïque, Université du Luxembourg. Campus Limpertsberg, BS 1.1.7, 162a, avenue de la Faïencerie, 1511 Luxembourg
physica status solidi (b) (Impact Factor: 1.49). 09/2008; 245(9):1772 - 1778. DOI: 10.1002/pssb.200879539


Thin film heterojunction solar cells based on chalcopyrites such as Cu(In,Ga)Se2 have achieved impressive efficiencies. However concern about the long term sustainability of photovoltaics based on scarce or expensive raw materials has prompted the search for alternative absorber materials. In this work, films of the p-type absorber Cu2ZnSnS4 (CZTS) were prepared by electroplating metallic precursors sequentially onto a molybdenum-coated glass substrate followed by an nealing in a sulfur atmosphere. The polycrystalline CZTS films were characterized by photoelectrochemical methods, which showed films were p-type with doping densities of the order of 1016 cm–3 and a band gap of 1.49 eV, close to the optimum value for terrestrial solar energy conversion. Preliminary results obtained for solar cells fabricated with this material are promising. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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    • "The factors that affect resistivity and mobility values, as well as the influence of the chemical composition on the transport mechanisms in CZTS thin films, require a full investigation. CZTS thin films have been grown by several deposition methods such as magnetron sputtering [2] [3] [9], thermal evaporation [10], sol gel [11], screen printed [12], electrodeposition [13], photochemical deposition [14], co-evaporation [15], and spray pyrolysis [7,16–19]. Although the pneumatic spray pyrolysis technique has been considered one of the most appropriate growth methods to develop low-cost devices, so far, low solar cell efficiency values have been reported [20] [21] [22]. "
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    ABSTRACT: Cu2ZnSnS4 (CZTS) thin films were grown onto glass substrates using pneumatic spray pyrolysis method under different growth conditions. The electrical properties have been investigated by means of dark and illuminated conductivity measurements in the 293–353 K temperature range and Hall measurements at room temperature. The influence of growth parameters on the grain boundary barrier height and other associated grain boundary parameters of the CZTS thin films was determined from electrical, optical, and morphological characterization. The CZTS electrical properties relation with secondary phases formation as well as with transport mechanisms is presented. Finally, CZTS electrical parameters impact on the properties of polycrystalline thin film solar cells is discussed.
    Full-text · Article · Jan 2015 · Solar Energy Materials and Solar Cells
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    • ". Varying the potential with respect to the reference electrode the authors of [9] derived the doping density values. The AQE depends on absorption coefficient Į as [22], AQE = 1-exp(-αW), where W is the width of the space charge region. For a direct allowed transition, the dependence of the absorption coefficient on the photon energy hȞ should follow the relation, αhȞ ∝ "
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    ABSTRACT: The elemental composition, structural, optical and electronic properties of p-type Cu3BiS3 thin films are investigated. The films are shown to be single phase orthorhombic, with a measured composition of Cu3.00Bi0.92S3.02. A surface oxidation layer is also clarified using energy dependent X-ray microanalysis. Photoreflectance spectra demonstrate two band gaps (EgX =1.24 eV and EgY =1.53 eV at 4 K) associated with the X and Y valence sub-bands. The photocurrent excitation measurements suggest a direct allowed nature of EgX. Photoluminescence spectra at 5 K reveal two broad emission bands at 0.84 and 0.99 eV quenching with an activation energy of 40 meV.
    Full-text · Article · Dec 2014 · Energy Procedia
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    • "The fabricated layer showed a weak quantum yield of 3.5% at a photon energy of 2.2 eV and slowly increased to over 4% for energies above 2.5 eV. For an ideal Schottky barrier electrolyte junction, the relation between the external quantum efficiency and the absorption coefficient a is given by [18] "
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    ABSTRACT: a b s t r a c t Cu 3 SbS 3 is a novel chalcogenide semiconductor with p-type conductivity and an energy bandgap of 1.84 eV. By incorporating selenium into this material to form Cu 3 Sb(Se x S 1 À x) 3 where x ¼Se/(Se þ S), the energy bandgap can be altered to be in the range 1.38–1.84 eV for 0 ox o0.49. The energy bandgap can hence be adjusted to be near the optimum for making the absorber layer for use in single and multi-junction photovoltaic solar cell devices. In this paper these materials were prepared using a two-stage process that involved magnetron sputtering of the Cu–Sb precursor layers followed by conversion to Cu 3 SbS 3 by annealing in the presence of elemental sulphur and to Cu 3 Sb(S x Se 1 À x) 3 by annealing in the presence of a mixture of sulphur and selenium. The films synthesised were characterised using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction, secondary ion mass spectroscopy and photo-electrochemical measurements. When the Cu 3 SbS 3 was formed on glass substrates it had a cubic crystal structure whereas when it was formed on Mo-coated glass it had the monoclinic crystal structure. Likewise the layers of Cu 3 Sb(S,Se) 3 formed on Mo-coated glass also had the monoclinic crystal structure. Spectral response curves were recorded over the spectral range 400–1400 nm for semiconductor—electrolyte junctions. Photovoltaic solar cell devices were made using p-type Cu 3 Sb(S x Se 1 À x) 3 as the absorber layer and n-type CdS as the buffer layer. The photovoltaic effect was observed in these devices. & 2013 Elsevier B.V. All rights reserved.
    Full-text · Article · Jun 2013 · Solar Energy Materials and Solar Cells
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