Electrodeposition of patterned CdSe nanocrystal films using thermally charged nanocrystals

Islam, Mohammad A.; Herman, Irving P.

doi:10.1063/1.1480878

Cited by 102 publications

(169 citation statements)

References 15 publications

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“…In addition, it is a method also employed to deposit colloidal QDs, especially CdSe, on different materials such as Au, 11,12 patterned electrodes, 13 stacked-cup carbon nanotubes, 14 and polymer templates. 15 Colloidal CdSe QDs have also been deposited by electrophoresis for photovoltaic purposes.…”

Section: ■ Introductionmentioning

confidence: 99%

Colloidal PbS and PbSeS Quantum Dot Sensitized Solar Cells Prepared by Electrophoretic Deposition

et al. 2012

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Here we report the development of quantum dot sensitized solar cells (QDSCs) using colloidal PbS and PbSeS quantum dots (QDs) and polysulfide electrolyte for high photocurrents. QDSCs have been prepared in a novel sensitizing way employing electrophoretic deposition (EPD) and protecting the colloidal QDs from corrosive electrolyte with a CdS coating. EPD allows a rapid, uniform, and effective sensitization with QDs, while the CdS coating stabilizes the electrode. The effect of electrophoretic deposition time and of colloidal QD size on cell efficiency is analyzed. Efficiencies as high as 2.1 ± 0.2% are reported.

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Section: ■ Introductionmentioning

confidence: 99%

Colloidal PbS and PbSeS Quantum Dot Sensitized Solar Cells Prepared by Electrophoretic Deposition

et al. 2012

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confidence: 99%

“…If nanoparticles are oppositely charged, the Coulomb potential would stabilize the BNSL while destabilizing the singlecomponent superlattices. The electrical charges might be present on sterically stabilized nanoparticles even in non-polar solvents [18][19][20] .To measure charges on the nanoparticles that form our BNSL, we studied the electrophoretic mobility of PbSe and Au nanocrystals. Laser Doppler velocimetry allows the distribution of electrophoretic mobilities within an ensemble of nanoparticles to be measured.…”

mentioning

confidence: 99%

Structural diversity in binary nanoparticle superlattices

Shevchenko

Talapin

Kotov

et al. 2006

Nature

2,019

2,088

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Assembly of small building blocks such as atoms, molecules and nanoparticles into macroscopic structures-that is, 'bottom up' assembly-is a theme that runs through chemistry, biology and material science. Bacteria 1 , macromolecules 2 and nanoparticles 3 can self-assemble, generating ordered structures with a precision that challenges current lithographic techniques. The assembly of nanoparticles of two different materials into a binary nanoparticle superlattice (BNSL) [3][4][5][6][7] can provide a general and inexpensive path to a large variety of materials (metamaterials) with precisely controlled chemical composition and tight placement of the components. Maximization of the nanoparticle packing density has been proposed as the driving force for BNSL formation 3,8,9 , and only a few BNSL structures have been predicted to be thermodynamically stable. Recently, colloidal crystals with micrometre-scale lattice spacings have been grown from oppositely charged polymethyl methacrylate spheres 10,11 . Here we demonstrate formation of more than 15 different BNSL structures, using combinations of semiconducting, metallic and magnetic nanoparticle building blocks. At least ten of these colloidal crystalline structures have not been reported previously. We demonstrate that electrical charges on sterically stabilized nanoparticles determine BNSL stoichiometry; additional contributions from entropic, van der Waals, steric and dipolar forces stabilize the variety of BNSL structures.Face-centred-cubic (f.c.c.) ordering of monodisperse hard spheres dispersed in a liquid permits larger local free space available for each sphere compared to the unstructured phase, resulting in higher translational entropy of the spheres. When the volume fraction of hard spheres approaches ,55%, this ordering enhances the total entropy of the system and drives the ordering phase transition. Entropy-driven crystallization has been studied in great detail both theoretically 12 and experimentally on monodisperse latex particles, whose behaviour can be approximated by hard spheres 13,14 . In a mixture containing spheres of two different sizes (radii R small and R large ), the packing symmetry depends on the size ratio of the small and large spheres (g ¼ R small /R large ) 3,8 . Calculations show that assembly of hard spheres into binary superlattices isostructural with NaCl, AlB 2 and NaZn 13 can be driven by entropy alone without any specific energetic interactions between the spheres 9,15 . Indeed, NaZn 13 -and AlB 2 -type assemblies of silica particles were found in natural Brazilian opals 16 and can be grown from latex spheres 17 . In a certain g range, the packing density of these structures either exceeds or is very close to the density of the close-packed f.c.c. lattice (0.7405), while structures with lower packing densities are predicted to be unstable 8,15 .Despite these predictions, we observed an amazing variety of BNSLs that self-assemble from colloidal solutions of nearly spherical nanoparticles of different materials (Fig. 1). Coheren...

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“…For some of these devices, the deposition of NC assemblies with controlled patterns is an essential step in the fabrication process. Common methods include drop casting (Murray et al 2001), spin coating (Finlayson et al 2000;Snee et al 2005), electrophoretic deposition (Islam and Herman 2002), and mist deposition (Zhu et al 2008). Direct-write methods such as ink-jet printing (Böberl et al 2007;Tekin et al 2007) are also attractive because they avoid mask screening, lithography, and pre-patterning of the substrate and can therefore simplify micropatterning and allow inexpensive and rapid prototyping (Chrisey 2000).…”

Section: Introductionmentioning

confidence: 99%

Micropattern Deposition of Colloidal Semiconductor Nanocrystals by Aerodynamic Focusing

McMurry

Norris

et al. 2010

Aerosol Science and Technology

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We report the use of aerodynamic lenses to deposit micropatterns of colloidal semiconductor nanocrystals (or quantum dots). CdSe and CdSe/ZnS core/shell nanocrystals, with core diameters of 3.5-5 nm, were dispersed in hexane and then nebulized to generate agglomerates a few tens of nm in diameter, consisting of hundreds of nanocrystals. These agglomerates were then focused aerodynamically by a lens system. Microscale towers, lines, and patterns were deposited on thin sapphire plates and silicon wafers. The heights and widths of the deposits were adjustable by varying the experimental parameters. Line widths below 10 µm at fullwidth half-maximum are demonstrated. Upon exposure to near-UV illumination, these deposits exhibited robust fluorescence in the visible, with the color depending on the diameter of the individual nanocrystal cores. A red shift of the photoluminescence peaks from the nanocrystal dispersion to the glassy solid deposits was also observed, which confirmed that the deposits consist of closely packed nanocrystals embedded in the organic matrices. This approach, which is not restricted to semiconductor nanocrystals, provides an alternative means for the deposition of microscale patterns of colloidal nanoparticles.

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Electrodeposition of patterned CdSe nanocrystal films using thermally charged nanocrystals

Cited by 102 publications

References 15 publications

Colloidal PbS and PbSeS Quantum Dot Sensitized Solar Cells Prepared by Electrophoretic Deposition

Colloidal PbS and PbSeS Quantum Dot Sensitized Solar Cells Prepared by Electrophoretic Deposition

Structural diversity in binary nanoparticle superlattices

Micropattern Deposition of Colloidal Semiconductor Nanocrystals by Aerodynamic Focusing

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