Resonance Energy Transfer (RET) is popularly known as fluorescence resonance energy transfer (FRET) that involves a nonradiative energy transfer from an electronic excited state of a donor molecule (D*) to the ground state of an acceptor molecule. Förster theory for energy transfer processes assumes dipole-dipole interactions and predicts that the rate of RET follows a 1/R 6 -type distance dependence, where R is the center-to-center distance between D and A. However, a significant deviation from 1/R 6 dependence is observed for donor-acceptor systems with increased asphericity. Bagchi and coworkers have formulated that rate of RET follows 1/R 4 dependence for nanoparticle-fluorophore systems. To quantify the energy transfer for M:PNC-Rhodamine systems rise time of acceptor is being exploited. The excited state concentration of the acceptor, A * (t), generated via FRET, is proportional to the time-resolved fluorescence intensity of donor IDA (t) in presence of acceptor. Moreover, this donor-acceptor system is relatively homogenous and random solution with no excluded volume. Considering the cubic and elongated dodecahedron structures for doped-PNCs, we have quantified the rate of energy transfer and efficiency of energy transfer (EFRET) by using formalism of 1/R 4 dependence for FRET. Where 𝜏 𝐴 𝑟𝑖𝑠𝑒 is the rise-time component of acceptor, 𝜏 𝐷𝐴 is the donor's lifetime with acceptor, 𝜏 𝐷 is the donor's lifetime (without acceptor), 𝑅 0 is the Förster distance, and 𝑅 𝐷𝐴 is the D-A distance. Such a huge variation in binding constant cannot be obtained without either compositional variation of crystal facets or preferential interaction of oleylamine/oleic acid with facets. The basis of this hypothesis stems from the recent observation that cyclohexamine gets preferentially absorbed at {111} facet of FaPbI3 perovskite. However, accurate quantification of surface composition or stoichiometry of facets {100} and {111} is quite difficult, hence, we have analyzed structural features through Rietveld Refinement. Hence, facet {100} offers a conducive chemical environment for Rhodamine B due to presence of number of cesium ions and thus fosters dipoledipole interaction such as FRET. However, presence of Pb(II) in facet {111} enforces specific adhesion with oleyamine due to chelation/metal-ligand type of interactions, hence, block the access of Rhodamine B to Ni:Co:PNC nanocrystal.