Instant interfacial self-assembly for homogeneous nanoparticle monolayer enabled conformal “lift-on” thin film technology

Abstract

Instant interfacial self-assembly of nanoparticle monolayer advances the thin film technology in a “lift-on” and conformal manner.

Self-Assembled Au Nanoparticle Monolayers on Silicon in Two- and Three-Dimensions for Surface-Enhanced Raman Scattering Sensing

“… 40 , 41 , 44 , 45 Densely packed AuNP films can be formed via self-assembly at a liquid/liquid interface, which can be later transferred to a planar substrate. 46 − 48 However, the postfunctionalization of the AuNPs with a structure-directing molecule, such as mercapto-polyethylene glycol, 1-dodecanethiol, acrylamide molecules, or perfluorodecanethiol, complicates the approach, while the deposition of the resulting AuNP monolayers on substrates with complex topographies, such as VA-SiNW arrays, has not been successfully demonstrated. 46 − 48 The self-assembly of presynthesized AuNPs on functionalized Si, on the other hand, offers a low-cost and simple route that is amenable for mass-production and is compatible with the coating of nanostructured silicon.…”

“… 46 − 48 However, the postfunctionalization of the AuNPs with a structure-directing molecule, such as mercapto-polyethylene glycol, 1-dodecanethiol, acrylamide molecules, or perfluorodecanethiol, complicates the approach, while the deposition of the resulting AuNP monolayers on substrates with complex topographies, such as VA-SiNW arrays, has not been successfully demonstrated. 46 − 48 The self-assembly of presynthesized AuNPs on functionalized Si, on the other hand, offers a low-cost and simple route that is amenable for mass-production and is compatible with the coating of nanostructured silicon. 21 , 23 , 44 , 46 − 49 The self-assembly process is self-limited, providing the opportunity to control AuNP coverage, and is potentially compatible with NPs of different sizes, compositions, and shapes.…”

“… 46 − 48 The self-assembly of presynthesized AuNPs on functionalized Si, on the other hand, offers a low-cost and simple route that is amenable for mass-production and is compatible with the coating of nanostructured silicon. 21 , 23 , 44 , 46 − 49 The self-assembly process is self-limited, providing the opportunity to control AuNP coverage, and is potentially compatible with NPs of different sizes, compositions, and shapes. 21 , 23 , 50 However, the preparation of substrates with homogeneous AuNP assemblies providing uniform E-field enhancements over large areas remains a challenge.…”

“…Top-down methods, such as electron-beam or nanoimprint lithography, have been successfully used for preparing well-defined Au or other metallic nanostructures on Si. ,− They require, however, expensive and elaborated lab equipment and clean-room conditions. ,,, Densely packed AuNP films can be formed via self-assembly at a liquid/liquid interface, which can be later transferred to a planar substrate. − However, the postfunctionalization of the AuNPs with a structure-directing molecule, such as mercapto-polyethylene glycol, 1-dodecanethiol, acrylamide molecules, or perfluorodecanethiol, complicates the approach, while the deposition of the resulting AuNP monolayers on substrates with complex topographies, such as VA-SiNW arrays, has not been successfully demonstrated. − The self-assembly of presynthesized AuNPs on functionalized Si, on the other hand, offers a low-cost and simple route that is amenable for mass-production and is compatible with the coating of nanostructured silicon. ,,,− The self-assembly process is self-limited, providing the opportunity to control AuNP coverage, and is potentially compatible with NPs of different sizes, compositions, and shapes. ,, However, the preparation of substrates with homogeneous AuNP assemblies providing uniform E-field enhancements over large areas remains a challenge. , To prepare such AuNPs@Si substrates, silanes containing amino- or mercapto-groups have been previously used to form siloxane bonds with the Si surface and to direct the assembly of AuNPs at the Si surface either via electrostatic interaction or covalent bonding. ,− Both the Si functionalization and the AuNP assembly step are sensitive to the experimental conditions. Among others, the quality of the silane layer is highly affected by the presence of water, temperature, heating speed, reaction time, and silane concentration, as well as the storage conditions after the functionalization itself has been completed. ,− The AuNP assembly on the Si surface is also sensitive to the pH and ionic strength of the solution, AuNP size and capping ligand, and immersion time in the AuNP solution. ,,, This self-assembly process is further complicated if topographically structured substrates, such as SiNWs, are to be uniformly coated because geometric restrictions may cause changes in accessibility and concentration profiles of the NPs to be deposited.…”

Etched-spiky Au@Ag plasmonic-superstructure monolayer films for triple amplification of surface-enhanced Raman scattering signals

“…To estimate the sensing capabilities and versatility of our proposed integrated triple amplification SERS platform, we investigated the SERS-sensing properties for the model molecule (4-aminothiophenol, 4-ATP). In recent years, our group has devoted itself to constructing macroscopic and uniform NPs monolayer films 32,33 and investigated their functional applications for SERS detection. 34,35 Thus, leveraging interfacial assembly for obtaining scale-up and uniform 2D NP arrays, both sensitivity and stability are heightened in our 2D plasmonic SERS sensing platform (Fig.…”