The project is devoted to fundamental research on hybrid solar cells, a solar cell technology based on conjugated polymers and inorganic semiconducting nanoparticles, containing aspects of nanotechnology and materials science. Hybrid solar cells combine the advantages of organic materials, like easy processability, and high absorption coefficients with the advantages of inorganic solar cell materials like high charge carrier mobilities and robustness. The active layers of hybrid solar cells are only a few hundred nanometres thick and can be prepared on flexible and transparent substrates. The efficiencies of hybrid solar cells increased steadily to about 4 - 5% in recent years, however, the breakthrough concerning power conversion efficiency did not take place so far. The limiting factor is most likely the complex interface between polymer and nanoparticles. Thus, fundamental research on the hybrid organic-inorganic interface is regarded to be the key to realise high efficiencies with this interesting type of solar cells.
Consequently, this project aims at chemical tailoring of polymer-nanoparticle interfaces in hybrid solar cells, which are prepared via the so called in situ route, where the nanostructures are synthesised directly in a matrix of a conjugated polymer. Interface engineering in nanocomposite layers prepared via this novel approach, is a completely new and unexplored field.
The influence of coordinating molecules with different anchor groups and dipole moments on surface trap states and charge separation will be thoroughly investigated. Special focus will be set on time resolved spectroscopic techniques, such as time-resolved fluorescence and microsecond to millisecond transient absorption spectroscopy for the study of energy and electron transfer processes, which are available at the Nanostructured Materials and Devices Group of the Department of Chemistry at Imperial College London, where the project will be conducted. Thereby, profound knowledge about the physical properties of the interface will be gained and the relations between the chemical tailoring and the optical and electronic properties as well as the morphology of nanocomposite layers will be studied. This fundamental knowledge about interface properties in nanocomposite layers and how they can be influenced could lead to significantly increased photovoltage and photocurrent of in situ prepared hybrid solar cells.