Materials Synthesis of Air-stable PbSe Quantum Dots ..

Synthesis of Air-stable PbSe Quantum Dots Using PbCl 2-oleylamine System ..

PPT – An overview of quantum dot synthesis, …

N2 - In this paper we describe the use of differently sized PbSe quantum dots as photosensitizers for anatase TiO2 nanowires under visible light illumination. After the organometallic synthesis of PbSe quantum dots with three different average diameters (1.8, 2.5 and 4.7nm), the nanocrystals were attached to the surface of nanowires with thioglycolic acid as a linker molecule. These quantum dot decorated nanowires were used as photocatalyst in the methyl orange degradation model reaction with promising results. The best performance achieved was 90% degradation of the initial concentration of methyl orange in six hours over 2.5nm PbSe quantum dot sensitized nanowires using a 40W quartz UV lamp equipped with a 400nm cut-off filter.

Synthetic Armor for Air-Stable Quantum Dots

AB - In this paper we describe the use of differently sized PbSe quantum dots as photosensitizers for anatase TiO2 nanowires under visible light illumination. After the organometallic synthesis of PbSe quantum dots with three different average diameters (1.8, 2.5 and 4.7nm), the nanocrystals were attached to the surface of nanowires with thioglycolic acid as a linker molecule. These quantum dot decorated nanowires were used as photocatalyst in the methyl orange degradation model reaction with promising results. The best performance achieved was 90% degradation of the initial concentration of methyl orange in six hours over 2.5nm PbSe quantum dot sensitized nanowires using a 40W quartz UV lamp equipped with a 400nm cut-off filter.

“Synthesis and Characterization of Monodisperse Nanocrystals and Close Packed Nanocrystal Assemblies,” C. B. Murray, C. R. Kagan, M. G. Bawendi, Annual Review of Materials Science 30, 545, (2000).

“Photoconductivity in CdSe Quantum Dot Solids,” C. A. Leatherdale, C. R. Kagan, N. Y. Morgan, S. A. Empedocles, M. A. Kastner, and M. G. Bawendi, Physical Review B, 62, 2669 (2000).


Pbs Quantum Dots Synthesis (PbS, 4N ..

Colloidal quantum dot solar cells (CQDSCs) are attracting growing attention owing to significant improvements in efficiency. However, even the best depleted-heterojunction CQDSCs currently display open-circuit voltages (VOCs) at least 0.5 V below the voltage corresponding to the bandgap. We find that the tail of states in the conduction band of the metal oxide layer can limit the achievable device efficiency. By continuously tuning the zinc oxide conduction band position via magnesium doping, we probe this critical loss pathway in ZnO–PbSe CQDSCs and optimize the energetic position of the tail of states, thereby increasing both the VOC (from 408 mV to 608 mV) and the device efficiency.

An overview of quantum dot synthesis, applications and safety

The conduction band position of the undoped ZnO was measured to be −3.7 eV (c). This is similar to the conduction band level of the PbSe quantum dots (−3.67 eV, see Supporting Information, Figure S4). The band diagram for the device with undoped ZnO is shown on the left of Figurea, where we illustrate the tails in the density of band states extending into the bandgap of the Zn1–xMgxO. Photoluminescence measurements further suggested that band tails were present in our films. The band emission for undoped ZnO was observed to extend 0.5 eV below the optical gap (b). In the presence of a conduction band tail, electrons transferred from the QDs to the ZnO may thermalize down the tail of sub-bandgap states to lower energy levels in the ZnO or they may be transferred to lower energy states in the ZnO directly at the interface. Either situation corresponds to a reduction in the extracted energy and achievable VOC, in a manner similar to that observed previously in light-absorbing layers with tail states in silicon and organic solar cells.[]

Polymer-assisted synthesis of water-soluble PbSe quantum dots

The solar cell parameters in b show that there was a compromise between increased VOC and reduced JSC with increasing Mg doping. A measurable photocurrent was still obtained when the Zn1–xMgxO conduction band was above that of the PbSe QDs (when x > 0), indicating that a tail of conduction band states in the Zn1–xMgxO was actively accepting electrons from the PbSe quantum dots and transporting electrons to the electrode. However, the density of accessible tail states is expected to decrease exponentially with doping as the conduction band was shifted to higher energies (as shown in the right of a), in agreement with the decrease in JSC with increasing Mg doping.