title: Probing Absolute Electronic Energy Levels in Hg-Doped CdTe Semiconductor Nanocrystals by Electrochemistry and Density Functional Theory.
abstract: The absolute electronic energy levels in Hg-doped CdTe semiconductor nanocrystals (CdHgTe NCs) with varying sizes/volumes and Hg contents are determined by using cyclic voltammetry (CV) measurements and density functional theory (DFT) -based calculations. The electrochemical measurements demonstrate several distinct characteristic features in the form of oxidation and reduction peaks in the voltammograms, where the peak positions are dependent on the volume of CdHgTe NCs as well as on their composition. The estimated absolute electronic energy levels for three different volumes, namely 22, 119 and 187 nm(3) with 2.7±0.3 % of Hg content, show strong volume dependence. The volume-dependent shift in the characteristic reduction and oxidation peak potential scan can be attributed to the alteration in the energetic band positions owing to the quantum confinement effect. Moreover, the composition (Cd/Hg=98.3/1.7 and 97.0/3.0) -dependent alteration in the electronic energy levels of CdHgTe NCs for two different samples with similar volumes (ca. 124±5 nm(3) ) are shown. Thus obtained electronic energy level values of CdHgTe NCs as a function of volume and composition demonstrate good congruence with the corresponding absorption and emission spectral data, as well as with DFT-based calculations. DFT calculations reveal that incorporation of Hg into CdTe NCs mostly affects the energy levels of conduction band edge, whereas the valence band edge remains almost unaltered.
authors.affiliation: Department of Chemistry, IIT Delhi, New Delhi, 110016, India. ppingole@chemistry.iitd.ac.in.|Physical Chemistry/Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany. ppingole@chemistry.iitd.ac.in.
authors.forename: Pravin P
authors.identifier: http://orcid.org/0000-0002-9755-4477
authors.initials: PP
authors.lastname: Ingole
authors.affiliation: Physical Chemistry/Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Lesnyak
authors.affiliation: Department of Physics, Savitribai Phule Pune University, Pune, 411007, India.
authors.forename: Laxman
authors.initials: L
authors.lastname: Tatikondewar
authors.affiliation: Physical Chemistry/Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Leubner
authors.affiliation: Physical Chemistry/Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Gaponik
authors.affiliation: Department of Physics, Savitribai Phule Pune University, Pune, 411007, India. anjali@physics.unipune.ac.in.
authors.forename: Anjali
authors.initials: A
authors.lastname: Kshirsagar
authors.affiliation: Physical Chemistry/Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eychmüller
keywords: CdHgTe nanocrystals; density functional calculations; energetic band positions; quantum confinement; redox potentials