Considering the distance between PNPls in their stacks determined by SAXS from Table (r ~ 5.1 nm), we can infer from Table that, even in a low PLQY scenario (e.g., 5%), the FRET efficiency is 52% for CsPbBr3 system (Efficiency = R0 6 /(r 6 + R0 6 )), considering isotropic conditions. If we consider parallel orientations (k² = 1), the efficiency reaches 56%. This value of PLQY was chosen based on the work of Bhon et al., who reported a PLQY of 7% for as-synthesized PNPls with n = 2. The same analysis was performed for CsPbI3 composition; however, as we do not have the PL from a pure n = 2 CsPbI3 PNPl, the energy transfer was considered in a system where both donor and acceptor are the PNPls with n = 3 (homo-FRET). The overlap between absorption and PL spectra is shown in Figure . Because the PLQY is probably higher for n = 3 CsPbI3 PNPls compared to n = 2 CsPbBr3 analogue, we estimated the values of R0 with a PLQY of at least 10%. Therefore, in the case of CsPbI3 system, FRET efficiency is calculated to be 60% in isotropic conditions and 63% in parallel orientation, considering the same distance (r ~ 5.1 nm) of the nanoplates' stacks. In the case of NPls in general, the transition dipoles are mostly oriented parallel to the plane of the NPl (k² = 1). Considering this orientation, we show in Figure the dependence of the FRET efficiency with the distance of the PNPls for the two systems described in Table with their probable PLQY.