Colloidal quantum dots (QDs) are semiconductor nanocrystals with size- and shape- tunable optical properties, fundamentally different from those of a macroscopic semiconductor crystal, and of significant interest in optoelectronics. For decades, CdSe-based QDs have been the workhorses in this field and this material platform has reached a good degree of maturity, making it suitable for applications in LEDs, displays and TV screens. However, Europa’s legislation does not allow the use of Cd-containing materials for opto-electronic applications. For this reason, the implementation of QDs in commercial devices requires to replace these QDs by legislation-allowed materials, which should have a similar optical performance.
InP QDs have shown to have a high photoluminescence quantum yield provided that they are coated with a suitable inorganic shell material, while the emission spectrum covers most of the visible region by tailoring the QD size. In this respect, understanding and optimizing the emission process is both of scientific interest and essential for large-scale applications.
The work presented in this thesis has provided new insights into the physical mechanisms of the radiative exciton decay in InP-based core/shell QDs. Specifically, it focuses on the investigation of the band-edge exciton fine structure and the related radiative exciton decay, with an emphasis on the active role of the different types of phonons interacting with dark exciton states.