Jon M. Azpiroz

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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)
Motivated by the recent experiments by Wang et al. (Angew. Chem., Int. Ed. 2012, 51, 6154-6157), in which the alkylamine-capped magic-size (CdSe)13 has been isolated for the first time, we report on the computational modeling of the putative low-lying isomers of (CdSe)13, both bare and ligand-protected. According to Density Functional Theory (DFT)(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)
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)
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)
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)
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)
We present a density functional theory (DFT) study aimed at understanding the injection and recombination processes that occur at the interface between PbS QDs and TiO2 oxide nanoparticles with different morphologies. The calculated injection rates fall in the picosecond timescale in good agreement with the experiments. In addition, our simulations show(More)
We investigate the photoinduced dipole (PID) phenomenon, which holds enormous potential for the optimization of quantum dot-sensitized solar cells (QDSSCs), by means of first-principles electronic structure calculations. We demonstrate that the sensitization of the TiO2 substrate with core/shell QDs produces almost no changes in the ground state but(More)