Chemically Linked AuNP−Alkane Network for Enhanced Photoemission and Field Emission

Abstract

Size and ligand effects are the basis for the novel properties and applications of metallic nanoparticles (NPs) in nanoelectronics, optoelectronics, and biotechnology. This work reports the first observation of enhanced photoelectron emission from metallic Au NPs ligated by alkanethiols. The enhancement is based on a conceptually new mechanism: the AuNP provides electrons while the alkane ligand emits electrons due to its low or negative electron affinity. Moreover, the AuNP-ligand chemical bonding is found to significantly facilitate the transmission of photoexcited electrons from the AuNP to the ligand emitter. Consequently the smooth NP film, which is a typical low-aspect-ratio two-dimensional structure, exhibits strong and stable field emission behavior under photoillumination conditions. The photoenhanced field emission is related to the interband and surface plasmon transitions in AuNPs, and a photoenhancement factor of up to approximately 300 is observed for the AuNP-based field emission. This is highly remarkable because field emission is often based on one-dimensional, high-aspect-ratio nanostructures (e.g., nanotubes and nanowires) with geometrical field enhancement effect. The chemical linkage of electron-supplying AuNP and electron-emitting alkane ligand represents a fundamentally new mechanism for efficient photoexcitation and emission. Being low-temperature/solution processable, and inkjet printable, AuNPs may be a flexible material system for optoelectronic applications such as photodetection and photoenhanced field emission.

On the role of low-energy electrons in the radiosensitization of DNA by gold nanoparticles

“…This is in fairly good agreement with the Au atom density if one considers that some electrons from the core will be absorbed by the surface layer. These results support the hypothesis [13] that formation of the Au-S bond contributes to the broadening of the Au peak. Fig.…”

The supramolecular structure and van der Waals interactions affect the electronic structure of ferrocenyl-alkanethiolate SAMs on gold and silver electrodes

“…33 In principle, the electronic properties of electrode-SAM interfaces are tunable by chemical modication of the SAM precursors, but the interfacial energetics (i.e., the energy level alignment) also depends strongly on the supramolecular structure of the SAM and how the molecules of the SAM interact with the electrode. [34][35][36][37][38][39][40][41] The difference between E F of the electrode and the energy of the frontier highest occupied molecular orbital (HOMO), E HOMO , or lowest unoccupied molecular orbital (LUMO), E LUMO , levels of SAMs is oen related to the current injection efficiencies, turnon values of switches and diodes, Fermi-level pinning and surface dipoles. 40,[42][43][44] Active groups such as ferrocenes add functionality to the SAMs, but they usually have larger diameters than the alkyl chain spacer and, as a consequence, they affect the packing structure of the SAM.…”

A Nanosegregant Approach to Superwettable and Water‐Attracting Surfaces

“…This indicates that there is a structural difference between the bulk film and nanosegregants even though both of them contain the PEDT and PSSH phases. The difference is reflected in the SE (secondary electron) emission results in the Supporting Information: the SE peak of the bulk film is quite broad, and is typical of continuous energy distribution of electronic states; the SE peak of the nanosegregants is very narrow, and is indicative of molecular-like discrete configuration [31] of electronic states. We believe this structural difference arises from the self-organization of the segregants during the natural-drying process.…”