TY - THES ID - 136501202 TI - Confinement of Cesium Lead Bromide clusters in Faujasite zeolites AU - De Ras, Michiel AU - Hofkens, Johan AU - Roeffaers, Maarten AU - KU Leuven. Faculteit Wetenschappen. Opleiding Master in de chemie (uitdovend programma vanaf 2018-2019) (Leuven) PY - 2019 PB - Leuven KU Leuven. Faculteit Wetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:136501202 AB - Lead halide perovskites (LHPs) are a new class of inorganic materials with the same chemical formula as the naturally occurring perovskite minerals: ABX3. These semiconductor materials have recently become very popular in the field of optoelectronics. It is expected that perovskites will play a leading role in the next generation of solar panels and light emitting diodes. However, the current applications of these materials stay limited due to their poor chemical and thermal stability. Earlier research conducted at the Hofkens group and Roeffaers lab pointed out that it is possible to confine luminescent metal clusters inside the pores of zeolites. These luminescent clusters were characterized by tunable optical properties and an enhanced chemical stability. Based on the promising results of this research, it was proposed to confine perovskite based clusters inside the pores of zeolites. As the host-guest chemistry of perovskites and zeolites has barely been explored so far, this project aims at discovering new synthetic procedures for the confinement of luminescent perovskite clusters in the pores of zeolite materials. To facilitate this process, it was chosen to focus on a specific host-guest couple. The guest species is the all inorganic CsPbBr3 perovskite. This synthetic perovskite has been studied before and both the luminescent and electronic are well documented. The emission spectrum of CsPbBr3 is characterized by a very narrow, symmetrical emission peak around 525nm. Furthermore, the synthetic procedures of these materials are fairly easy. The host species is the well known faujasite zeolite. As zeolites with the faujasite framework have been used before to confine luminescent metal clusters, it is assumed that they are suitable host materials for the confinement of perovskite clusters. Furthermore, the faujasite zeolite has one of the largest cavities of all zeolites. It is suspected that this will positively influence the confinement process. Additionally, the chemistry of zeolite materials can also be tuned very precisely. The negative charge of the 3D aluminosilicate framework can be altered by changing the silicon to aluminium ratio of the framework. This will also influence the amount of extraframework cations present in the material. These extraframework cations can be replaced by other cations through the process of ion exchange. An important phenomenon in this project is the quantum confinement effect. This effect explains the blueshift in absorption and emission spectra of luminescent semiconductor nanocrystals. It was found that the bandgap energy of semiconductor materials significantly increases if the physical size of the crystal approaches the exciton Bohr radius. The quantum confinement effect is observed in CsPbBr3 nanocrystals smaller than 10nm. Additionally, it was suggested that confined CsPbBr3 clusters might display a blueshift in the emission spectrum as large as 100nm. This effect will make it able to confirm whether observed luminescent species are confined in the zeolite or not. ER -