Life and death of defects and charges in solution-processed nano-crystalline semiconductors studied by photoluminescence spectroscopy and microscopy

Electron dynamics in metal halide perovskites (MHPs) is poorly understood despite substantial progress in the development of MHP-based devices.

One reason for this is a continuous chemical and structural transformation inherent in these materials due to their low-temperature processability and ionic nature.

Depending on the conditions, defect states can be created (resulting in material degradation) or annihilated (material self-healing).

We will study charge and defect dynamics and their chemical transformations across a very wide range of timescales, from picoseconds to days.

Photoluminescence (PL) spectroscopy and imaging will be used to provide us with sensitivity levels that vastly exceed other techniques.

Measurements at the single nano/micro crystal level will give us information on individual channels of defect-assisted energy loss and their dynamics.

We will search for and consider long-term chemical processes induced by excited charge carriers that, in their turn, influence the short-term charge dynamics.

New time-resolved and steady-state techniques based on multi-pulse excitation of PL over a large range of pulse repetition rate will be applied.

Possessing these new data, we can come up with new theoretical models that explicitly include photochemical processes, which will make a large impact to the field.

Understanding the defect dynamics will hopefully allow for the rational design of self-healing semiconductors and devices in the future.