Time-Resolved Photo­­luminescence Course

Time-correlated single photon counting methods for unraveling the photo physics of DNA-Stabilized Silver Nanoclusters

Tom André Jos Vosch

In this lecture, I will talk about how time-correlated single photon counting is used to better understand the unusual photophysical behavior of DNA-stabilized silver nanoclusters. 

Understanding Time-resolved Photoluminescence in Lead-halide Perovskite Thin Films for Solar Cells

Chris Dreessen

Lead-halide perovskite solar cells are promising candidates for the next generation of photovoltaic technologies. As single-junction devices, they could enable applications based on lightweight and flexible substrates; alternatively, they can be integrated with established Si solar cells in tandem architectures to achieve power-conversion efficiencies beyond the practical limits of conventional single-junction technologies. Although laboratory-scale perovskite solar cells have already reached efficiencies comparable to those of Si devices, substantial challenges remain, including scalable fabrication and long-term operational stability. In parallel, fundamental questions concerning electronic trap states and recombination mechanisms in lead-halide perovskites remain unresolved. Here, we discuss carrier-recombination dynamics in photovoltaic-relevant lead-halide perovskite thin films, with particular emphasis on trap-assisted and radiative recombination. The analysis is based on distinctive material properties, which are uncommon in most conventional semiconductors, especially low doping densities, low exciton-binding energies, and strongly anharmonic lattice dynamics. Under these conditions, shallow trap states located close to the band edges can dominate carrier recombination. The corresponding recombination rate scales with the product of the electron and hole concentrations, similar to radiative band-to-band recombination. These dynamics produce power-law rather than exponential decays in time-resolved photoluminescence measurements, causing the apparent decay time to increase continuously at long delay times. This non-exponential behavior has direct implications for TRPL measurements and their interpretation. Reliable characterization requires sufficiently low excitation repetition rates to prevent carrier accumulation and a large detection dynamic range to resolve the extended late-time decay. For the analysis, the full transient contains substantially more information than can be represented by a single effective lifetime. In principle, fitting the complete TRPL decay can constrain the underlying trap and recombination parameters. However, correlations between model parameters can produce degeneracies and render individual parameters structurally or practically non-identifiable. Consequently, fitting procedures must be extended beyond point estimates to quantify parameter likelihoods, correlations, and confidence regions for physically plausible parameter combinations.

Perovskite Quantum Dots as Quantum Light Sources

Gabriele Rainò

Besides conventional optoelectronic devices such as LEDs and lasers, colloidal quantum dots (QDs) are being explored as non-classical light sources (i.e., single-photon emitters) that could play a pivotal role in future quantum technologies, including quantum computing, quantum cryptography, and quantum sensing. Here, we investigate the carrier dynamics of individual perovskite quantum dots at both room and cryogenic temperatures, with particular emphasis on the radiative and non-radiative relaxation pathways of excitons and excitonic complexes (trions and biexcitons). We also investigate hybrid systems combining single QDs with organic dyes, exploiting Förster resonance energy transfer (FRET) as a nanoscale probe to map ligand conformations.