Synthesis and Characterizations of Colloidal Perovskite Nanocrystals for Photovoltaic Application

Abstract

Recently, all-inorganic perovskite nanomaterials have been studied because of their higher stability than organic-inorganic hybrid perovskite. However, modifying previous method to simpler and finding other all-inorganic perovskite composition are demanded due to its complicate method. Thus, in this work we studied tuning all visible range with cesium lead halide nanocrystals and synthesizing new perovskite composition with different inorganic elements which are not studied before. Nowadays, it is important to develop simple synthesis method to apply luminescence nanoparticle on various application such as light emitting diode and laser. In the first part, we studied halide ion exchange on cesium lead halide perovskite nanocrystals. With halide exchange, we can tune cesium lead brome perovskite which is green emitting nanocrystals to other halide perovskite which emit different color in all visible range with different concentration LiI or LiCl. Halide exchange happens in room temperature within few seconds. Interestingly, reverse reactions also happen when we use LiBr solution. Moreover, Maximum 5 cycles can happen in one sample. Exchanged nanocrystals exhibit very bright luminescence and it has narrow half full with full-with-half-maximum (15-20nm) and their radiative life is 1-16ns. We fabricate photo-detector with cesium lead iodide nanocrystals. It shows high responsibility with light. Therefore, we can check the potential of cesium lead halide perovskite as photo application. Unlike cesium lead halide perovskite nanocrystal, few perovskite nanocrystals which have different compositions have been studied. Therefore, searching new class of perovskite nanocrystals is demanded for various applications. In chapter 2, we firstly synthesized colloidal rubidium lead halide perovskite nanowires. Rubidium lead halide perovskite nanowire has orthorhombic structure and its lengthy is few macro meter. Rubidium lead halide perovskite nanowire strongly absorb the light below 450nm and it shows good responsibility with light. Therefore, we suggest that rubidium lead halide perovskite nanowire can be potential candidate for optoelectronic materials. ⓒ 2017 DGIST