In line with all these considerations, the work of Singldinger et al. shows evidence of energy transfer from n = 2 to n = 3 CsPbBr3 PNPls, reaching up to 69% efficiency. Interestingly, the most efficient energy transfer regime was achieved with a sample with twenty times more acceptors then donors, which suggests an effect of efficiency enhancement through a scaffold of acceptors around a common donor. Methods to improve the PLQY of these PNPls 55 can increase further the efficiency of FRET in their superlattices. In addition, changing the length of the capping ligands is also a good strategy to modulate FRET efficiency and rates. In an overall perspective, the efficiency we estimated for FRET in those systems using their superlattice parameters seem to be realistic and is in agreement with experimental findings reported in the literature. Equally important, our analysis show that the level of proximity reached in the PNPls stacks (5.1 nm) in hexane is only achieved at high concentrations of their colloidal suspensions, which allows us to conclude that FRET is very unlikely in diluted PNPls dispersions in this solvent, as previously proposed by Bonato et.al. Nonetheless, FRET formalism relies on the ideal dipole approximation (IDA), which we must consider in these NPls systems. In the IDA, the electronic coupling between donor and acceptor is considered as a dipole-dipole coupling from center to center of the donor-acceptor pair, and this approximation may fail depending on the distance and orientation factors. For a randomly oriented, isotropic donor-acceptor system (i.e., k² = 2/3), IDA fails for distances shorter than ~ 2 nm. However, when the donor-acceptor system presents restricted relative mobility, the distance in which the IDA fails can be higher than 5 nm, which may pose strong limitations to FRET experiments in these systems. In addition, it is important to consider the influence of the different confinement geometries of the donor-acceptor systems on the distance dependence for FRET rates and efficiency. For instance, Hernández-Martínez et. al., have predicted a dependence proportional to 1/r for the energy transfer between two nanoplates, which case of PNPls. This prediction is supported by experimental data in the literature. This less sensitive distance dependence changes the energy transfer efficiency between PNPls, especially in their stacks. Figure shows a comparison of the FRET efficiency with different distance dependencies for CsPbBr3 donor-acceptor system.