Nanoscale manipulation of CdSe quantum dots in layer-by-layer films: influence of the host polyelectrolyte on the luminescent properties

Abstract Thioglycolic acid-capped CdSe quantum dots (QDs) were assembled on glass substrates with two distinct polyelectrolytes, viz poly(allylamine hydrochloride) (PAH) and poly(amidoamine) (PAMAM), generation 4 dendrimer, via the layer-by-layer (LbL) technique. Films containing up to 30 polyelectrolyte/QD bilayers were prepared. The growth of the multilayers was monitored with UV–vis spectroscopy, which showed an almost linear increase in the absorbance of the 2.8 nm QDs at 535 nm with the number of deposited bilayers. AFM measurements estimated a film thickness of 3 nm per bilayer for the PAH/CdSe films. The adsorption process and the optical properties of the PAMAM/CdSe LbL films were further analyzed layer-by-layer using surface plasmon resonance (SPR), from which a thickness of 3.2 nm was found for a PAMAM/CdSe bilayer. Photoluminescence measurements revealed higher photooxidation of the quantum dots in PAH/CdSe than in PAMAM/CdSe films.

[1]  S. O’Brien,et al.  Comparison and Stability of CdSe Nanocrystals Covered with Amphiphilic Poly(Amidoamine) Dendrimers , 2002 .

[2]  L. Halaoui.  Layer-by-Layer Assembly of Polyacrylate-Capped CdS Nanoparticles in Poly(diallyldimethylammonium chloride) on Solid Surfaces , 2001 .

[3]  S. Velumani.  Structural and optical properties of hot wall deposited CdSe thin films , 2003 .

[4]  Alf Mews,et al.  Supramolecular Complexes from CdSe Nanocrystals and Organic Fluorophors , 2001 .

[5]  Vicki L. Colvin,et al.  X-ray Photoelectron Spectroscopy of CdSe Nanocrystals with Applications to Studies of the Nanocrystal Surface , 1994 .

[6]  P. Stroeve,et al.  Nucleation and Growth of Cobalt Hydroxide Crystallites in Organized Polymeric Multilayers , 2000 .

[7]  K. Kern,et al.  Spatially Selective Electroless Deposition of Cobalt on Oxide Surfaces Directed by Microcontact Printing of Dendrimers , 2002 .

[8]  M. Bruening,et al.  pH-Dependent Growth and Morphology of Multilayer Dendrimer/Poly(acrylic acid) Films , 2003 .

[9]  H. Ploehn,et al.  Polyamine−Quantum Dot Nanocomposites: Linear versus Starburst Stabilizer Architectures , 1999 .

[10]  M. Bawendi,et al.  Electroluminescence from CdSe quantum‐dot/polymer composites , 1995 .

[11]  Helmuth Möhwald,et al.  Electroluminescence Studies on Self-Assembled Films of PPV and CdSe Nanoparticles , 1998 .

[12]  Surface Chemistry Studies of Quantum Dots (QDs) Modified with Surfactants , 2003 .

[13]  H. Nalwa,et al.  Handbook of polyelectrolytes and their applications , 2002 .

[14]  Xiaogang Peng,et al.  Formation of high-quality CdTe, CdSe, and CdS nanocrystals using CdO as precursor. , 2001, Journal of the American Chemical Society.

[15]  Gero Decher,et al.  Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites , 1997 .

[16]  S. V. Mello,et al.  Micro‐Raman Scattering Imaging of Langmuir–Blodgett Surface Relief Gratings , 2001 .

[17]  Vipin K. Rastogi,et al.  Layer-by-Layer Films of Chitosan, Organophosphorus Hydrolase and Thioglycolic Acid-Capped CdSe Quantum Dots for the Detection of Paraoxon , 2003 .

[18]  Scott L. Cumberland,et al.  Synthesis and Characterization of a 1:6 Au−CdSe Nanocomposite , 2003 .

[19]  Wilfried van Sark,et al.  Photooxidation and Photobleaching of Single CdSe/ZnS Quantum Dots Probed by Room-Temperature Time-Resolved Spectroscopy , 2001 .

[20]  T. Chinowsky,et al.  Quantitative interpretation of the response of surface plasmon resonance sensors to adsorbed films , 1998 .

[21]  V. Tsukruk,et al.  Self-Assembled Multilayer Films from Dendrimers , 1997 .

[22]  S. Regen,et al.  Dendrimers as Building Blocks for Multilayer Construction , 1994 .

[23]  A. Alivisatos,et al.  Improved efficiencies in light emitting diodes made with CdSe(CdS) core/shell type nanocrystals and a semiconducting polymer , 1997 .

[24]  P. Stroeve,et al.  Nucleation and Growth of Lead Sulfide Nano- and Microcrystallites in Supramolecular Polymer Assemblies , 2000 .

[25]  D. Whitten,et al.  Photophysics of quantized colloidal semiconductors. Dramatic luminescence enhancement by binding of simple amines , 1986 .

[26]  S. L. Nelson,et al.  Polyelectrolyte-quantum dot multilayer films fabricated by combined layer-by-layer assembly and Langmuir-Schaefer deposition. , 2004, Langmuir : the ACS journal of surfaces and colloids.