Jon M. Azpiroz

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Ligand exchange is a much-used method to increase the conductivity of colloidal quantum-dot films by replacing long insulating ligands on quantum-dot surfaces with shorter ones. Here we show that while some ligands indeed replace the original ones as expected, others may be used to controllably remove the native ligands and induce epitaxial necking of(More)
In this work, we build a benchmark data set of geometrical parameters, vibrational normal modes, and low-lying excitation energies for MX quantum dots, with M = Cd, Zn, and X = S, Se, Te. The reference database has been constructed by ab initio resolution-of-identity second-order approximate coupled cluster RI-CC2/def2-TZVPP calculations on (MX)6 model(More)
The rational design of ligand molecules has earned lots of attention as an elegant means to tailor the electronic and optical properties of semiconductor quantum dots (QDs). Aromatic dithiocarbamate molecules, in particular, are known to greatly influence the optoelectronic properties of CdSe QDs, red-shifting the absorption features and enhancing the(More)
ZnO has attracted a great deal of research as a potential replacement of TiO2 for dye-sensitized solar cells (DSSCs), owing to the unique combination of interesting electronic properties (i.e., high electron mobility) and structural richness. Here, we present a DFT/TDDFT study about the interaction of the prototypical N3 and N719 Ru(II) sensitizers on ZnO(More)
The potential energy surface of the hypothetical NaMgAlSiPSCl system (heavy periodane) is exhaustively analyzed via the gradient embedded genetic algorithm (GEGA) in combination with density functional theory (DFT) computations. The electronegativity differences among the elements in both the second and third rows of the periodic table indicate that(More)
Inspired by their geometrical perfection, intrinsic beauty, and particular properties of polyhedranes, a series of carbo-cages is proposed in silico via density functional theory computations. The insertion of alkynyl units into the C-C bonds of polyhedranes results in a drastic lowering of the structural strain. The induced magnetic field shows a(More)
A new hierarchical method to determine molecular similarity is introduced. The goal of this method is to detect if a pair of molecules has the same structure by estimating a rigid transformation that aligns the molecules and a correspondence function that matches their atoms. The algorithm firstly detect similarity based on the global spatial structure. If(More)
Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely(More)
ZnS and CdS small nanoclusters have been predicted to trap alkali metals and halogen atoms. However would this kind of nanocompounds be able to encapsulate dianions and dications? This would be very interesting from an experimental point of view, since it would allow the isolation of such divalent ions. Moreover, the resulting endohedral complexes would(More)
Excimers are evanescent quasi-particles that typically form during collisional intermolecular interactions and exist exclusively for their excited-state lifetime. We exploited the distinctive structure of metal quantum clusters to fabricate permanent excimer-like colloidal superstructures made of ground-state noninteracting gold cores, held together by a(More)