All-inorganic cesium lead halide perovskites (ILHPs), are gaining wide variety of role as strong contenders due to their extraordinary photovoltaic features in optoelectronic research with tunable band-gap, large absorption cross-section, long carrier lifetime, and high carrier mobility. Most of the initial studies focused on bulk-like perovskite materials, while the rapidly growing colloidal perovskite nanocrystals impress additional interest because of their unique properties. In this thesis, colloidal lead halide perovskite nanocrystals’ optoelectronic properties are investigated and associated with their size and dimensionality. The photoluminescence characteristics of colloidal lead halide perovskite nanocrystals can be tuned by reducing their dimensionality. Thin layer fabrication of CsPbBr3 films which consist of 2D lead halide perovskite nanoplatelets, is achived by a novel coating approach via electrospraying from precursor solution. Electrospraying method represents not only a new and fast perovskite film fabrication but also dimensional tunability by changing the amount of oleylamine which is intercalating agent. Moreover, thicknessdependence of the structural, electronic and vibrational properties of orthorhombic CsPbI3, which is one of the most stable phase at room temperature, is investigated by means of state-of-the-art first-principles calculations. It is also investigated that the electronic band gap increases with decrease in perovskite thickness due to quantum size effect. Lastly, it is investigated that water induced transition to form large bundles of CsPbBr3 nanowires show a a redshifted photoluminescence. Water molecule causes the detachment of ligands from the perovskite surface which leads to form bundles. In summary, this thesis provides an understanding of dimension dependent optoelectronic properties of lead halide perovskite.