title: ab initio study of hot carriers in the first picosecond after sunlight absorption in silicon.
abstract: Hot carrier thermalization is a major source of efficiency loss in solar cells. Because of the subpicosecond time scale and complex physics involved, a microscopic characterization of hot carriers is challenging even for the simplest materials. We develop and apply an ab initio approach based on density functional theory and many-body perturbation theory to investigate hot carriers in semiconductors. Our calculations include electron-electron and electron-phonon interactions, and require no experimental input other than the structure of the material. We apply our approach to study the relaxation time and mean free path of hot carriers in Si, and map the band and k dependence of these quantities. We demonstrate that a hot carrier distribution characteristic of Si under solar illumination thermalizes within 350 fs, in excellent agreement with pump-probe experiments. Our work sheds light on the subpicosecond time scale after sunlight absorption in Si, and constitutes a first step towards ab initio quantification of hot carrier dynamics in materials.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Bernardi
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Derek
authors.initials: D
authors.lastname: Vigil-Fowler
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lischner
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Kavli Institute for Energy Nanosciences, Berkeley, California 94720, USA.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Neaton
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie