Time-resolved Phase Microscopy using Patterned-illumination

―Visualization of Photo-excited Carriers in Photocatalysts and Photovoltaics ―

Abstract

A time-resolved phase microscopy has been developed for the observation of the photo-excited charge carrier dynamics in solar-devices such as photocatalysts and photovoltaics. By utilizing the pump-probe technique for the imaging, the time-resolution is only limited by the pulse width, 5 ns. An arbitrary spatial pattern of a pump pulse light excites the charge carriers, which provides various image recovery techniques for the refractive index image with a low S/N ratio. We applied the image recovery using the robust principal component analysis and the sparsity in the Fourier domain. By utilizing the data assimilation with the charge decay model, the lifetime and diffusion coefficients were mapped out for the photo-excited electrons in inhomogeneous titanium oxide film.