Conversely, cathodic photocurrent generation was not observed hence, the QD-modified electrode performs electrical rectification under a photon energy input. Anodic photocurrent generation was observed when an ITO electrode functionalized with ZnTe/ZnS nanocrystals was irradiated in the visible region in a photoelectrochemical cell, indicating that the quantum dots perform spectral sensitization of the electron injection into the ITO electrode. XPS results have evidenced the distinct nature of core and core/shell QDs, confirming the formation of QDs with shells of different thicknesses and their evolution due to oxidation upon air exposure. The ZnS shell preserves the optical properties of the core and improves the chemical and photochemical stability of the nanoparticles in air equilibrated solution, whereas they appear to be quite fragile in the solid state. Both the ZnTe core and ZnTe/ZnS core/shell quantum dot samples absorb in the visible region and are not luminescent. The optical data indicate that these core/shell quantum dots belong to type I, i.e., both the electron and the hole are confined within the ZnTe core. The effect of various synthetic parameters on the reaction outcome was investigated, and the resulting nanocrystals were characterized by TEM, EDX, XPS, and spectroscopic measurements. These nanocrystals can represent alternatives to cadmium-based quantum dots but their preparation and properties are challenging and relatively unexplored. We report the synthesis of spherical ZnTe nanocrystals and the successive coating with a ZnS shell to afford core/shell quantum dots. E-mail: Fax: +39 06 49913328 Tel: +39 06 490324 d CNR-IMM, via Gobetti 101, 40129 Bologna, Italy e Interuniversity Center for the Chemical Conversion of Solar Energy, Bologna Unit, Via Selmi 2, 40126 Bologna, Italy f Faculty of Non-Ferrous Metals, AGH University of Science and Technology, al.
E-mail: Fax: +456 Tel: +540 b Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland c Dipartimento di Chimica, Università La Sapienza, P.le Aldo Moro 5, 00185 Roma, Italy. Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy. * ae a Nanosciences Laboratory, Dipartimento di Chimica “G. C, 2014, 2, 2877-2886 Synthesis and properties of ZnTe and ZnTe/ZnS core/shell semiconductor nanocrystals † Journal of Materials Chemistry C, Cambridge, v. Improving carrier extraction in a PbSe quantum dot solar cell by introducing a solution-processed antimony-doped SnO2 buffer layer. Effect of band anisotropy on electronic structure of PbS, PbSe, and PbTe quantum dots, Physical Review B, v. Semina: Exact and Technological Sciences, v. Study of the optical properties in charged CdTe quantum dots. Photovoltaic efficiency of intermediate band solar cells based on CdTe/CdMnTe coupled quantum dots. Magneto-optical properties in IV-VI lead-salt semimagnetic nanocrystals. A numerical study into the influence of quantum dot size on the sub-bandgap interband photocurrent in intermediate band solar cells, AIP Advances, v.
Electronic structure and optical properties of PbS and PbSe quantum dots, Journal of the Optical Society of America B, v. CdTe/PbTe superlattice modeling and fabrication for solar cells applications, Journal of Nano Research, v. (eds), Contemporary nanomaterials in material Engineering applications, Engineering materials. Quantum dots synthesis and application, In: MUBARAK, N. Multiple exciton generation in quantum dot-based solar cells, Nanophotonics, Berlin, v. The lead salt quantum dot intermediate band solar cell, IEE, v.
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