Interfaces in photovoltaic materials - resonant electron spectroscopy with hard X-rays: studies of charge transfer in the attosecond regime

Tidsperiod: 2015-01-01 till 2018-12-31

Projektledare: Andreas Lindblad

Finansiär: Vetenskapsrådet

Bidragstyp: Projektbidrag

Budget: 7 732 400 SEK

FeS2, pyrite or fool´s gold have excellent light-absorbing properties. In this project we will study the charge transfer of hard X-ray photoexcited electrons from pyrite into metal or organic (graphene) interfaces.Composite materials will inevitably have interfaces between the components; the electronic structure will be affected by this and control the performance of the material when incorporated in, for instance, solar cells. The study will be concentrated on nanocrystalline pyrite incorporated in a graphene-oxide sheet synthesised by a standard sol-gel method, and sulphurized hematite on FTO glass capped with graphene. Both systems offers interesting oportunities of studying semiconductor interfaces with direct applicability in photoelectrochemical and photovoltaic devices. For the devices the performance will be increased with incorporation of Ag nanoparticles to enhance light-harvesting further with plasmonic effects. hard X-rays, i.e. photon energies above 2 keV) give access to electrons that emanate from deeper within the solid (interfaces) owing to the possibility to give them higher kinetic energy.By tuning the photon energy to a core-unoccupied state resonance the photoexcited state decays by emission of an Auger electron whose final state may be de-localized. The time-scale of the process is accessible via the electron kinetic energy spectrum: in the case of sulphur processes on the attosecond time scale is observable.