Time-resolved PL by time correlated single photon counting (TCSPC) [possible with selected excitation wavelength and sample ambient as required]
PL decay is extremely important information and relevant to most essential carrier dynamic processes. Such PL decay measurement has been proven to be very useful for the information of materials/nanocomposites/devices for electron-hole recombination (radiative and nonradiative), defect trapping and surface trapping (surface passivation), charge transfer and carrier transport etc. Therefore, such techniques have been intensively applied for characterization of new materials and devices, determination the quality of the materials or devices and surface passivation, determination of the photogenerated charge transfer and carrier transport. Particularly useful for new materials, nanomaterials and nanocomposites for photovoltaics, photocatalysis, photonics and biomaterials etc.
Optical probe of ionic dynamics in perovskite
Perovskites have been showed mixed electric-ionic conductor and mobile ions play critical role in determining the properties and performance of the devices. Using time-resolved micros-pectroscopy we can probe the dynamics of the mobile ions in perovskites and their nanostructures.
Fluorescence lifetime imaging microscopy (FLIM)
Combined TCSPC and confocal microscopy, FLIM can provide spatial distribution of PL intensity (photon number) and photon lifetime, with 200 nm spatial resolution and ps time resolution. With superior detection capability, such FLIM has detection sensitivity down to single molecule, single nanoparticle/quantum dot level – Single molecule spectroscopy.
Ultrafast (fs-ps) transient absorption and time-resolved PL
Ultrafast spectroscopic techniques, for example, ultrafast transient absorption (pump probe), time-resolved PL, (also streak camera, optical pump- THz probe, Kerr gating, four wave mixing etc.), provides valuable information with time resolution of fs-ps for various dynamic processes, extremely important for ultrafast carrier dynamic processes from dephasing to depopulation, usually for new materials/devices in new photovoltaic, photocatalytical, photonic, quantum information systems. The generally most relevant processes include (carrier, exciton, phonon relaxation of phase and population), such as carrier-phonon scattering, cooling of hot electrons, exciton formation and dissociation, electron transfer etc.
Depth resolved FLIM (steady state and time-resolved PL)
Directly detecting the fluorescence and time-resolved PL can be achieved through two-photon excitation (combined with femtosecond pulses and confocal microscope). This is very useful non-destructive detection without dissecting or specifically fabricating layered sample. This technique can achieve depth resolved measurement, that is, not only on the surface but also under the surface, without dissecting.