Optical and Electrooptical Properties of Porous‐Silicon/Conjugated‐Polymer Composite Structures

Abstract

We report on the fabrication and characterization of porous‐silicon/conjugated‐polymer hybrids, created by combining a host columnar matrix of mesoporous silicon and a network of organic nanowires made from poly(N‐vinylcarbazole) (PVK). A uniform and homogeneous filling of the pores by the polymers was accomplished by electrochemical polymerization of organic monomers inside the pores by using cyclic voltammetry. Spectroscopic measurements showed that polymerization inside the confined environment of the nanometric pores results in a tighter and denser packing of the polymer due to a change of the polymerization process from the vinyl groups to the conjugated carbazole groups, giving rise to a redshift of the absorption spectra and better electrical conductivity. Current‐voltage characterization of the hybrids under dark conditions and under illumination were investigated. We demonstrate a simple method to control the band alignment between the organic polymer and the porous silicon, altering it from a type‐I to a type‐II interface by changing the doping polarity of the silicon substrate (from p‐type to n‐type, respectively). An efficient photoinduced charge separation was observed for the type‐II interface (n‐type porous‐silicon–polymer interface), while no such effect was observed for the type‐I organic–inorganic interface.

Silver nanocube dimer nanojunctions as plasmon-enhanced Raman sensors

“…S7 and Table S1), which resulted from the increase in the sensitivity of Raman signals in nanocomposites under the plasmon-induced electromagnetic field as the electric conductivity of the environment surrounding the dimer nanojunction increased (electric conductivity: PS, PVP (B10 À16 (S cm À1 )) o HS-poly-p-TPA, PTPA (B4 Â 10 À11 (S cm À1 ))o HS-PVK, PVK(B10 À9 (S cm À1 )). [40][41][42] The enhancement factors of chemical vibration modes of PS, PVP, TPA, and PVK in the Raman spectra of different nanocomposites under the plasmon-induced electromagnetic field are organized in Fig. 3(G) and the ESI, † Table S1.…”

Enzyme Mediated Encapsulation of Gold Nanoparticles by Polyaniline Nanoshell

“…the pH of the environment [9]. The use of anionic templates for adsorption of positively charged monomers followed by in situ chemical, electrochemical and enzymatic polymerization, yielding surface confined nanolayers of conducting polymers was already exemplified for various substrates, such as: metal [10] and oxide surfaces [11], porous silicon [12] carbon nanotubes [13] and DNA [14]. These experiments are setting the stage for the use of new in situ template synthesis on negatively charged AuNPs.…”

Diversification of Device Platforms by Molecular Layers: Hybrid Sensing Platforms, Monolayer Doping, and Modeling

“…One of the early examples of an integrative approach in the context of nanotechnology and surface chemistry was the formation of nanowire-based sensors where surface chemical events are translated into electrical signals in a nanowire-based device. This strategy combined concepts from device engineering, surface chemistry, and nanosystems. , Since these early examples, there has been an increasing rate of introduction of new hybrid systems that merge molecular assemblies and nanosystems and whose properties include sensing pH, single enzymes, toxins, explosives, interfacing neurons, electrical and electronic characterization, and more. − This proliferation of new applications can be attributed to the synergism in hybrid device systems that includes organic–inorganic components, allowing them to benefit from the versatility and flexibility of the rich molecular toolbox available for organic synthesis and, at the same time, to take advantage of the robustness and well-established processing methodologies of inorganic materials …”

“…12−17 This proliferation of new applications can be attributed to the synergism in hybrid device systems that includes organic−inorganic components, allowing them to benefit from the versatility and flexibility of the rich molecular toolbox available for organic synthesis and, at the same time, to take advantage of the robustness and wellestablished processing methodologies of inorganic materials. 18 A true meĺange of surface chemistry and nanotechnology holds the potential to extend the scope of each and to provide unprecedented design flexibility and processing control. Specifically, hybrid devices could exploit chemical tools to address technological challenges that otherwise limit the practicality of certain nanotechnology advances.…”