Metal halide perovskite (MHP) semiconductors, such as methylammonium lead iodide (MAPbI3), have recently received tremendous attention in materials science, as these have yielded high efficiency solar cells, X-ray detectors and LEDs. However, one of the most fundamental material properties of MHPs still remains debated: whether their band gap is direct or slightly indirect. The nature of the band gap determines both the light absorption properties and the lifetime of light-generated charge carriers. Both of these properties are important for e.g. the efficiency of a solar cell or the suitability of MHPs to be used as photocatalysts.
This project aims to reveal the nature of the band gap and investigate whether this can be manipulated. You will use optical spectroscopy techniques to study the absorption of light and the recombination of charge carriers as a function of temperature and pressure, and develop models to analyze the data. Finally, you will make a link between the band gap and the photocatalytic activity of MHPs.