Publication Informations

Title
Core–shell PbS/Sn:In2 O3 and branched PbIn2S4 /Sn:In2O3nanowires in quantum dot sensitized solar cells
Authors: Matthew Zervos; Eugenia Vasile; Eugeniu Vasile; Andreas Othonos
Year: 2016
Research Area: Optical Characterization
Type of Publication: Article
Journal Details
Journal: Nanotechnology
Volume: 28
Number: 5
Pages: 054004
Abstract:
Core–shell PbS/Sn:In 2 O 3 and branched PbIn 2 S 4 /Sn:In 2 O 3 nanowires have been obtained via the deposition of Pb over Sn:In 2 O 3 nanowires and post growth processing under H 2 S between 100 °C–200 °C and 300 °C–500 °C respectively. The PbS/Sn:In 2 O 3 nanowires have diameters of 50–250 nm and consist of cubic PbS and In 2 O 3 while the PbIn 2 S 4 /Sn:In 2 O 3 nanowires consist of PbIn 2 S 4 branches with diameters of 10–30 nm and an orthorhombic crystal structure. We discuss the growth mechanisms and also show that the density of electrons in the n-type Sn:In 2 O 3 core is strongly dependent on the thickness of the p-type PbS shell, which must be smaller than 30 nm to prevent core depletion, via the self-consistent solution of the Poisson–Schrödinger equations in the effective mass approximation. The PbS/Sn:In 2 O 3 and PbIn 2 S 4 /Sn:In 2 O 3 nanowire networks had resistances of 100–200 Ω due to the large carrier densities and exhibited defect related photoluminescence at 2.2 eV and 1.5 eV respectively. We show that PbS in contact with polysulfide electrolyte has ohmic like behavior but the PbS/Sn:In 2 O 3 nanowires gave, rectifying current voltage characteristics as a counter electrode in a quantum dot sensitized solar cell using a conventional ITO/TiO 2 /CdS/CdSe photo anode, an open circuit voltage of ≈0.5 V, and short circuit current density of ≈1 mA cm −2 . In contrast the branched PbIn 2 S 4 /Sn:In 2 O 3 nanowires exhibited a higher current carrying capability of ≈7 mA cm −2 and higher power conversion efficiency of ≈2%.
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