Luminescence spectroscopy has become a fundamental method for analyzing the photophysical properties of various samples, from simple organic molecules to semiconductor materials and PV devices. Steady-state methods like excitation and emission spectroscopy offer insights, yet they provide only a partial view post-photoexcitation.
Time-resolved luminescence spectroscopy delves deeper into photophysical processes, revealing the intrinsic characteristic of luminescence lifetime. This indicates the duration of species remaining in excited states before returning to ground state, influenced by the environment. Spectroscopic and microscopic methods based on luminescence lifetime offer further information inaccessible via steady-state experiments.
Acquiring time-resolved data at regions of interest helps infer structural-to-photophysical relationships and detect changes in the local environment. Fluorescence lifetime imaging microscopy (FLIM) combines lifetime and spatial localization, aiding investigations in life sciences. In materials science, termed time-resolved photoluminescence (TRPL) imaging, it characterizes parameters like charge carrier dynamics and mobility in semiconductors, often occurring on timescales from picoseconds to nanoseconds.
Demonstrating a spectrometer-microscope assembly, we characterize materials in terms of lifetime, spectral, and spatial resolution. Using a laser driver with burst capabilities allows measurement of long luminescence decays. This multidimensional approach's benefits will be shown through examples across various materials science applications.

With higher excitation intensity the TRPL image of the sample becomes more uniform due to saturation of energy traps.

Frank Birke

Appearances