Structural and optoelectronic properties of unsaturated ZnO and ZnS nanoclusters

accedi l full-text(opens in a new window)|View at Publisher| Export | Download | Add to List | More... Journal of Physical Chemistry C Volume 116, Issue 15, 19 April 2012, Pages 8741-8746 Structural and optoelectronic properties of unsaturated ZnO and ZnS nanoclusters (Article) Malloci, G.a , Chiodo, L.b, Rubio, A.c, Mattoni, A.a a Istituto Officina Dei Materiali (CNRIOM), Unità di Cagliari, Cittadella Universitaria, I-09042 Monserrato (Ca), Italy b Center for Biomolecular Nanotechnologies UNILE, Istituto Italiano di Tecnologia, European Theoretical Spectroscopy Facility, Via Barsanti, I-73010 Arnesano, Italy c European Theoretical Spectroscopy Facility (ETSF), Nano-Bio Spectroscopy Group, CFM-CSIC-UPV/EHU-MPC and DIPC, Avenida Tolosa 72, E-20018 San Sebastián, Spain View additional affiliations View references (70) Abstract We report a systematic computational study of the structural and optoelectronic properties of unsaturated ZnO and ZnS nanoclusters with hexagonal prism structure, as a function of length and diameter. We computed the fundamental gap using density functional theory (DFT) in the framework of the ?SCF scheme and the optical gap by means of time-dependent DFT (TDDFT). We found that all ZnO nanostructures transform from wurtzite to graphitic phase. On the contrary, ZnS nanocrystals with diameters above ∼1 nm are found to transform to a zeolite BCT phase. These different structural properties reflect in a very different size dependence of the electronic and optical properties, with a strong discontinuity for ZnS particles. The correlation between morphology and optoelectronic properties is demonstrated by considering models of saturated clusters preserving the wurtzite phase. We additionally compared DFT/TDDFT results with many-body perturbation theory methods showing a general good agreement among the two techniques for this class of nanocrystals of the two materials