We are interested in time-resolved photoluminescence (PL) spectroscopy to assess the optical and electronic properties of various materials. PL measurements provide crucial insights into the emission dynamics, efficiency, and defect states of quantum dots and nanostructures. Our research focuses on investigating zero-dimensional (0D) perovskite nanocrystals (PNCs), analyzing their emission behavior under varying environmental conditions such as temperature and pressure fluctuations. We have observed delayed emission components linked to thermally activated defect states, with lifetimes extending to ~70 ns at room temperature, gradually diminishing at cryogenic temperatures. These findings aid in identifying materials suited for advanced optoelectronic applications, including solar cells and light-emitting devices. (J. Phys. Chem. Lett. 2023, 14, 12, 2933–2939)
Using time-correlated single-photon counting (TCSPC), we study PL decay dynamics to understand exciton-biexciton interactions in quantum shells (QSs). Our findings indicate that exciton-exciton interactions in QSs deviate from conventional scaling laws, suggesting weaker Coulomb interactions and extended multiexciton lifetimes. Large-core QSs, in particular, demonstrate biexciton lifetimes exceeding 15 ns, highlighting their potential for efficient light emission and lasing applications. (J. Am. Chem. Soc. 2023, 145, 24, 13326–13334 and ACS Materials Lett. 2023, 5, 5, 1411–1419)
Additionally, we employ time-resolved PL techniques to investigate carrier dynamics and recombination pathways in nanostructured materials, including transition metal dichalcogenide (TMD) monolayers. By analyzing PL stability and decay kinetics, we assess the effects of encapsulation and doping strategies in improving emission properties. Our studies reveal that alumina encapsulation effectively enhances PL stability, prolonging emission lifetimes by mitigating non-radiative recombination. Understanding these mechanisms allows for the rational design of materials with optimized optical performance for next-generation photonic and quantum technologies.
(a) PL intensity decay of 8.7-nm-core QSs resulting from two excitation regimes: low-power, ⟨Neh⟩ = 0.24 (red circles) and high-power, ⟨Neh⟩ = 3.9 (blue circles). The blue curve represents a fit using a parametric model curve (eq 1). The best fit is obtained using f = 2.7, which deviates from the statistical scaling of multiexciton rates ( f = 3.0, green curve). (b) PL intensity decay of 8.7-nm-core QSs resulting from a range ofexcitation powers, corresponding to ⟨Neh⟩ = 0.4−3.9. The fitting parameter for each case is shown in the legend.