Silicon nanocrystals for photonics and photovoltaics: Ab initio results

The research of new materials to complement or replace traditional bulk semiconductors for photonic and photovoltaic applications is a very active field. Suitable candidates to carry this task are represented by silicon nanocrystals. Thesematerials present unique chemical and physical properties which are intrinsically associated with their low dimensionality and with the quantum confinement effect. Despite their great relevance, full comprehension of these properties is still lacking and many fundamental issues need deep investigation. In this context the role of theoretical modeling and simulations is extraordinarily important. It is a widespread belief among the nanoscience research community that ab initio approaches constitute a unique and very powerful instrument to control and design the properties of novel materials and devices with an accuracy that complements experimental observations. Here we present density-functional and many-body perturbation theory calculations that have been carried out in these last years in our group in order to study the structural, electronic, optical, and transport properties of such nanocrystals, showing that many experimental results can be simulated and understood through theoretical studies.