Electron Transport Experimental Investigation of Perovskites using Light and Electron Injection at the Nanoscale

The main goal of EXPLEIN is to unravel the limiting factors in the charge carrier transport in perovskite thin films, stacks, and solar cells, aiming to pre-select suitable material compositions for and optimisation of light-converting devices.

First, I will gain deep understanding of the role of grain boundaries typically limiting charge carrier diffusion due to an increased number of recombination centres in thin films and lamellae, which I will then apply to interfaces in stacks and devices, ultimately allowing me to monitor and improve the performance of perovskite-based solar cells.

The centre piece of this work is a scanning electron microscope equipped with cathodoluminescence (CL) and pulsed electron beam capabilities.

I will expand those with electrical sample biasing for operando conditions and develop a novel light in-coupling module.

This unique, versatile method will facilitate local injection of electrons and photons into the same sample area, thereby allowing for the in-depth study of the differences in morphology (via in-situ secondary electron imaging), optical (via CL and CL lifetimes) and electrical properties upon selective sub-bandgap-energy illumination, applied electrical bias, and local e-beam placement.

The diffusion length, a key parameter for solar cell absorbers, will be measured directly and via CL-lifetimes which I will subsequently link to the samples average grain size of various perovskite compositions.

The perovskite database will serve as platform for comparison and exchange of knowledge, ultimately allowing to advance and expand the research field.The multitude of the proposed experiments will allow me to gain new and detailed insights into the micro- and nanoscopic charge carrier transport in several types of perovskites, giving me the opportunity to contribute to the advancement of solar cells necessary for the challenging transition to cost-effective and sustainable energy.