Statistical Analysis of Photoluminescence Decay Kinetics in Quantum Dot Ensembles: Effects of Inorganic Shell Composition and Environment

Discerning the kinetics of photoluminescence (PL) decay of packed quantum dots (QDs) and QD-based hybrid materials is of crucial importance for achieving their promising potential. However, the interpretation of the decay kinetics of QD-based systems, which usually are not single-exponential, remains challenging. Here, we present a method for analyzing photo-luminescence (PL) decay curves of fluorophores by studying their statistical moments. A certain combination of such moments, named as the n-th order moments' ratio, Rn, is studied for several theoretical decay curves and experimental PL kinetics of CdSe quantum dots (QDs) acquired by time-correlated si n g l e photon counting (TCSPC). For the latter, three different case studies using the Rn ratio analysis are presented, namely, (i) the effect of the inorganic shell composition and thickness of the core-shell QDs, (ii) QD systems with Fo''rster resonance energy transfer (FRET) decay channels, and (iii) system of QDs near a layer of plasmonic nanoparticles. The proposed method is shown to be efficient for the detection of slight changes in the PL kinetics, being time-efficient and requiring low computing power for performing the analysis. It can also be a power f u l tool to identify the most appropriate physically meaningful theoretical decay function, which best describes the systems under study.

Automated summary

In this study, a method for analyzing the photoluminescence decay curves of fluorophores is presented using the statistical moments. The proposed method shows high efficiency and accuracy in analyzing the decay kinetics of CdSe quantum dots and QD systems, and it can identify the most appropriate theoretical decay function for describing the systems under study.