Exploring the Plasmonic Density of States To Direct Singlet or Triplet Excitonic Energy Transfer from Perovskite Nanocrystals

The processes of excitonic energy transfer across the interfaces of semiconductor–metal heterostructures have garnered fundamental scientific and technological interest in a wide gamut of photon conversion applications. Metal halide perovskites have triggered great curiosity as an intriguing class of photoluminescent semiconductors because of their outstanding emission properties, viz., the reciprocity between photon absorption and emission, improved color purity, near-unity photoluminescence quantum yield, narrow spectral bandwidth, and tunability of the emission wavelength that arises due to quantum confinement effects, high excitonic binding energy, and the possibility of charge localization in the nanostructures. On the other hand, the field of plasmonics explores the collective oscillation of free electrons on metallic surfaces that enables subwavelength optical confinement and enhanced light–matter interactions. Energy transfer from perovskite nanocrystals to metallic acceptors via a photoexcited singlet or triplet state offers the opportunities to govern the deactivation pathways through Förster resonance energy transfer or Dexter energy transfer at the semiconductor–metal interface. Therefore, a mechanistic understanding of the underlying photophysical processes associated with phenomenological electron–matter and light–matter interactions is indispensable to govern the counterbalance between the radiative and nonradiative decay channels. In this work, we have explored to ameliorate the impact of local density of optical states as a function of size-selective silver nanospheres as an enticing approach to direct energy transfer pathways from CsPbCl₃ perovskite nanocrystals from both theoretical and experimental perspectives. The specificity of interaction of size-selective silver nanoparticles offers the opportunity to unravel the plasmonic density of states with the perovskite nanocrystal surface. The cumulative variation of size and concentration of the silver nanoparticles paves an avenue to realize critical interplay of energy transfer processes at the perovskite–metal heteronanostructures. Thus, in reality, the phenomenological photophysical processes can be viewed as the interconnect between photonics and plasmonics as the two paradigms of light–matter interactions to design a landscape toward the rational optimization of plausible nanophotonic applications.