Electronic structure at nanocontacts of surface passivated CdSe nanorods with gold clusters

Abstract

We report the effects of variation in length on the electronic structure of CdSe nanorods derived from atomic clusters and passivated by fictitious hydrogen atoms. These nanorods are augmented by attaching gold clusters at both the ends to form a nanodumbbell. The goal is to assess the changes at nanolevel after formation of contacts with gold clusters serving as electrodes and compare the results with experimental observations 1 . Calculations involving nanorods of length 4.6Å to 116.6Å are performed using density functional theory implemented within plane-wave basis set. The binding energy per atom saturates for nanorod of length 116.6Å. It is interesting to note that upon attaching gold clusters, the nanorods shorter than 27Å develop metallicity by means of metal induced gap states (MIGS). Longer nanorods exhibit a nanoscale Schottky barrier emerging at the center. For these nanorods, interfacial region closest to the gold electrodes shows a finite density of states in the gap due to MIGS, which gradually decreases towards the center of the nanorod opening up a finite gap. Bader charge analysis indicates localized charge transfer from metal to semiconductor.

Band Edge Energetics of Heterostructured Nanorods: Photoemission Spectroscopy and Waveguide Spectroelectrochemistry of Au-Tipped CdSe Nanorod Monolayers

“…Since injection into the SET levels of the Au tip is unlikely to cause bleaching of the NR absorbance, the SET features observed by STS are unlikely to be detectable by spectroelectrochemistry. However, if the MSI states are electronically coupled to the NR conduction band (i.e., tunneling occurs between MSI states and the conduction band), 6,81 then injection into the MSI states will contribute to bleaching of the lowest energy NR absorbance. We therefore posit that bleaching transitions of Au-tipped NRs having an onset near À4.6 eV are due to charge injection into MSI states.…”

Computational studies of stable hexanuclear CulAgmAun(l + m + n = 6;l,m,n > 0) clusters

“…Monometallic and bimetallic NP have been the subject of intense research efforts from both theoretical and experimental viewpoints, and technological applications in a variety of fields have been envisioned because of the existing simple methods to synthesize functional nanoparticles of commercial importance . It has also been shown that it is feasible to control their physicochemical characteristics for specific purposes, such as in medicine, catalysis, and other industrial applications in the fields of food, and electronics, for example, as nanocontacts in metal‐semiconductor devices …”

“…[5][6][7] It has also been shown that it is feasible to control their physicochemical characteristics for specific purposes, such as in medicine, [8] catalysis, [9] and other industrial applications in the fields of food, [10] and electronics, for example, as nanocontacts in metalsemiconductor devices. [11,12] Structural studies are a recurring topic in current research due to the correlation between the nanoparticle size, shape, and composition, and its physical and chemical properties. The issue of finding the energetically most favorable structures has been addressed through diverse computational techniques, which have led to the discovery of unusual geometries.…”

Surface plasmon resonance enhancement of photoluminescence intensity and bioimaging application of gold nanorod@CdSe/ZnS quantum dots

“…Richard A. Vaia and co-authors reported a five times higher fluorescence enhancement by organizing QDs on GNRs, and Anjali Kshirsagar et al reported the electronic structure of free-standing and gold-attached passivated CdSe nanorods [24–25]. These studies covered the synthesis of GNR@CdSe/ZnS nanoparticles using different methods; however, most of these synthesis methods are complicated, and it is difficult to reproduce their preparation and desired applications.…”