Photophysics of Metal Halide Perovskites

Global warming and the corresponding energy transition requires continuous search of new technology and materials. One such class of materials is metal halide perovskites, showing excellent properties to be used in highly efficient solar cells and LED’s. We investigated a wide range of different compositions of metal halide perovskites and determined their properties. The first few chapters of this thesis are dedicated to low-dimensional perovskites. By analysing their crystal structures, the colour of the compounds could be explained. More importantly, however, it was found that the photoluminescence of these crystals is largely impacted by defects, for which they are the reason for the appearance of broad luminescent bands causing the light to be red or white. If precise control of these defects can be obtained, one can envision efficient white light sources as well as colour pure LED’s. In the last few chapters, the composition was changed of tin-based perovskites thin films. This sub-class have shown an interesting property – slow carrier cooling – that could enable highly efficient solar cells beyond 60%. We showed that this property can mainly be attributed to the filling of the electronic bands, related to Sn-based perovskites. The compositional variation allowed us to elucidate that also the vibronic bands are important in the slow cooling of carriers, hereby providing valuable fundamental information of these materials and compose new design principles.