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PicoQuant for Materials Science

Investigate fast processes in materials with time-resolved methods

Why use time-resolved methods for materials science?

A central aspect of materials science lies in investigating the relationship between the atomic or molecular structure of a material and its macroscopic properties. Two powerful tools for elucidating excited state dynamics and processes in a wide variety of materials are time-resolved spectroscopy and microscopy.
We, here at PicoQuant, can provide you with an instrument combination that marries

the capabilities of a spectrometer with a microscope's ability to probe and scan small areas. This combination opens the door for exciting opportunities to investigate the spatial dependence of luminescence behavior in all kinds of samples.

Find out what and where it happens with an easy to use set-up!

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Examples of Time-Resolved Photoluminescence (TRPL) measurements

1) Measuring charge carrier dynamics

Photoluminescence in can be used to directly monitor charge carrier dynamics in semiconductors. The charge carrier lifetime for particular classes of semiconductors is highly dependent on the nature and dimensions of materials and interfaces involved, as well as on surface effects, passivation, presence of dopants, impurities, or defect sites. Therefore, TRPL measurements using time-correlated single photon counting (TCSPC) are highly suited for the analysis of phenomena that determine fast charge carrier dynamics down to the sub-nanosecond time scale and also provide an indication of a semiconductors quality.

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2) Imaging of charge carrier dynamics

TRPL measurements of semiconductors can be expanded by applying scanning techniques, which enables lifetime imaging of charge carrier dynamics. In conjunction with intensity dependent photoluminescence lifetime measurements, the effects of carrier diffusion and its influence on the total lifetime can be determined. Using TRPL imaging, charge carrier diffusion processes as well as the effect of localized inhomogeneities and defect sites can be identified. The multi-dimensional approach makes this imaging a versatile and powerful methodology for the analysis of semiconductor materials.

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3) Determining electron-hole diffusion lengths in solar cells

TRPL quenching experiments are a valuable tool for determining diffusion lengths of photo-excited electrons and holes in semiconductor solar cells. The example shows data obtained from mixed halide and triiodide organometal perovskite layers in presence of either an electron or hole quenching layer, or a non-quenching PMMA coating. The measured decay dynamics can be fitted to a diffusion model, allowing to derive diffusion lengths. Here, the diffusion length of the electrons and holes in the mixed halide perovskite was 1µm while the triiodide material featured a much shorter length of 100 nm, correlating well with the performance of these materials as solar cells.

S. D. Stranks et al., Science, 342 (2013), p.341

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