Less than a decade ago, lead halide perovskite semiconductors caused a sensation: Solar cells exhibiting astonishingly high levels of efficiency. Recently, it became possible to synthesize nanocrystals of this material as well. Interestingly; simply by controlling the size and shape of these crystals, new aspects of this material literally came to light. These nanocrystals have proven to be interesting candidates for light emission. 

 In this thesis, the recombination, dephasing and diffusion of excitons in perovskite nanocrystals is investigated using time-resolved spectroscopy. All these dynamic processes have a direct impact on the light-emitting device performance from a technology point of view. However, most importantly, the insights gained from the measurements allowed the author to modify the nanocrystals such that they emitted with an unprecedented quantum yield in the blue spectral range, resulting in the successful implementation of this material as theactive layer in an LED. This represents a technological breakthrough, because efficient perovskite light emitters in this wavelength range did not exist before.

Bernhard Johann Bohn received his B.Sc. from the Technical University of Munich. For his M.Sc. he also went to ETH Zurich and Harvard University where he did research on metasurfaces in the group of Prof. Federico Capasso. After some time at the Max Planck Institute of Quantum Optics he finished his PhD in the group of Prof. Jochen Feldmann at the Nano-Institute in Munich at the Ludwig-Maximilians University. His work on dynamic exciton processes in perovskite nanocrystals was also awarded with the Nano Innovation Award 2020 by the Center for NanoScience.