In this work, we show the conditions in which PNPls self-assemble in organic solvents without the use of antisolvents. To unravel these properties, we used small-angle X-ray scattering (SAXS) technique, which is a powerful tool to investigate colloidal suspension of nanomaterials and their assemblies. We investigated suspensions of PNPls with CsPbBr3 and CsPbI3 compositions in different conditions and four different solvents: hexane, decane, dodecane, and hexadecane. We found that, by increasing the viscosity of the solvents, the degree of aggregation of PNPls is enhanced, forming stacks with good colloidal stability. Also, we show that the concentration for the aggregation in hexane is around 80 mg/mL, which is a rather high concentration for colloidal suspensions. Considering the stacking parameters obtained from SAXS and STEM, we estimate that FRET from thinner to thicker PNPls (or homo-FRET for CsPbI3) can be highly enhanced, with predicted efficiencies higher than 50% in colloidal suspension, for both CsPbBr3 and CsPbI3 compositions.