Predicting signatures of anisotropic resonance energy transfer in dye-functionalized nanoparticles

TL;DR

This paper theoretically investigates the anisotropic nature of resonance energy transfer (RET) in dye-functionalized nanoparticles, showing how polarization-dependent photoluminescence differences reveal intrinsic anisotropic signatures in hybrid nanomaterials.

Contribution

The study introduces a realistic kinetic model to identify and quantify the anisotropic signatures of RET in semiconductor nanoparticles decorated with dyes, highlighting their dependence on dye-NP distance and robustness with multiple dyes.

Findings

Photoluminescence differences for orthogonal polarizations reveal RET anisotropy.

Predicted anisotropic signature can reach up to 75%.

Anisotropic RET signature persists with multiple dyes.

Abstract

Resonance energy transfer (RET) is an inherently anisotropic process. Even the simplest, well-known F\"orster theory, based on the transition dipole-dipole coupling, implicitly incorporates the anisotropic character of RET. In this theoretical work, we study possible signatures of the fundamental anisotropic character of RET in hybrid nanomaterials composed of a semiconductor nanoparticle (NP) decorated with molecular dyes. In particular, by means of a realistic kinetic model, we show that the analysis of the dye photoluminescence difference for orthogonal input polarizations reveals the anisotropic character of the dye-NP RET which arises from the intrinsic anisotropy of the NP lattice. In a prototypical core/shell wurtzite CdSe/ZnS NP functionalized with cyanine dyes (Cy3B), this difference is predicted to be as large as 75\% and it is strongly dependent in amplitude and sign on the dye-NP distance. We account for all the possible RET processes within the system, together with competing decay pathways in the separate segments. In addition, we show that the anisotropic signature of RET is persistent up to a large number of dyes per NP.