UNDERPIN: UNDERstanding quantum Properties of Interfaces from first principles

• Applicant: Professorin Dr. Silvana Botti
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 393285225

In the domain of photovoltaics it is by now clear that the optimization of existing technologies and the development of new ones passes through a better control of the physics of interfaces. At the basis of any control strategy lies the need for a deep understanding of the different physical phenomena involved and their interdependence. This proposal aims at determining by means of ab initio calculations the interplay between interface morphology and electron-hole dynamics, in order to understand better the mechanisms controlling charge separation and recombination at interfaces in solar cells.To this end, in close collaboration with experimental partners, we will focus on a variety of hetero-interfaces relevant for photovoltaics, including Cu(Ga,In)Se2/CdS and Cu(Ga,In)Se2/back contact junctions, interfaces between Cu2ZnSnSe4 and secondary phases, as well as between perovskite absorbers and electron/hole transport layers.In the framework of generalized density functional theory and time-dependent density functional theory, we are developing a new local hybrid functional, derived from GW theory, and designed to account for electronic screening through its dependence on a density estimator of the local dielectric function. This functional will be further tested on simple interfaces, for which experimental data are available, and then used to calculate electronic excitations at realistic interfaces in solar cell devices. Thanks to our new hybrid functional, we will gain decisive understanding on electron-hole transport, separation and recombination. By shedding light on the limiting factors for energy conversion, we will finally be able to bring suggestions on how to overcome these limitations.This project is part of an ambitious long-term strategy in my recently established group and it will have the beneficial consequence to strengthen existing collaborations and promote new ones with experimentalists working on photovoltaics in Europe.

• DFG Programme: Research Grants
• International Connection: Luxembourg, Netherlands
• Cooperation Partners: Professorin Dr. Maria A. Loi; Professorin Dr. Susan Schorr; Professorin Dr. Susanne Siebentritt