Synthesis and characterization of low-dimensional organic-inorganic perovskites for detection and photovoltaic applications

Low-dimensional perovskite such as layered halide perovskite and perovskite nanocrystals have attracted attention in the past decade. These materials have impressive optoelectronic properties such as high photoluminescence and improved stability relative to their 3D counterpart. These properties arise from the confinement of the inorganic perovskite domains (nanoparticles or planes) in between passive organic molecules. In this thesis, we investigate large organic molecules as ligands for perovskite nanocrystal or layered perovskite spacers. These organic molecules based on organic dyes were selected as an alternative to the traditional isolator and optically inactive organic molecules (alkylamine or phenethylamine). In the case of light-emitting materials such as organic inorganic nanostructured scintillators, we used a Nile red-based ligand to replace a fraction of the traditional oleylamine. This linked dye perovskite system demonstrated a higher energy transfer efficiency relative to the unlinked (dispersion) of the dye and the perovskite nanocrystals. This resulted in a three-fold enhancement of the perovskite photoluminescence quenching and a 24% enhanced emission of the Nile red upon selective excitation of the perovskite nanocrystals. These gains arise from the promotion of a Förster resonance energy transfer over a less efficient emission/reabsorption (i.e. trivial) energy transfer as demonstrated by our spectroscopic analysis. This demonstration offers alternatives to the low light yield organic scintillators in which the red shifting occurs by a cascade of energy transfers. The energy transfer efficiency in the bounded system was calculated to be 64%. In the case of layered perovskite for photovoltaic applications, we designed organic spacers based on dithiophene diketopyrrolopyrrole (DPP). The incorporation of such a large aromatic system as a spacer cation in layered perovskite is challenging as the DPP core is about 13 Å whereas the two spacer binding sites are only 7.1 Å apart. To address this issue, we designed a first spacer focusing on reducing the apparent size of the conjugated system to favor its incorporation in a layered perovskite material. This approach allowed us to form a layered perovskite with a type II heterostructure, an enhanced charge carrier lifetime of 36 ns relative to butylammonium (17 ns) but a modest sum mobility. Investigating the origins of the low sum mobility, we realized that hole mobility in the organic slabs was a problematic factor. We redesigned the spacer aiming to favor staking in the organic slabs. This led to the formation of a second layered perovskite with a type II heterostructure and an enhanced carrier lifetime of 49 ns. In addition, our layered perovskite shows a mobility of 3.9 · 10-4 cm2V-1s-1 which represents a five-fold enhancement relative to our previous design. We also observed evidence of a charge transfer from the excited organic spacer to the inorganic conduction band. This obse