Ultrafast Tracking of Exciton and Charge Carrier Transport in Optoelectronic Materials on the Nanometer Scale

TL;DR

This paper introduces a cutting-edge optical microscope capable of tracking ultrafast exciton and charge carrier transport at nanometer spatial resolution and femtosecond temporal resolution, enabling detailed study of transport phenomena in optoelectronic materials.

Contribution

The authors develop a novel optical transient absorption and reflection microscope with sub-10 nm spatial and 12 fs temporal resolution for ultrafast transport studies.

Findings

Revealed exciton transport of up to 32 nm in pentacene

Tracked carrier motion in p-doped silicon

Enabled in-situ chemical verification via stimulated Raman spectroscopy

Abstract

We present a novel optical transient absorption and reflection microscope based on a diffraction-limited pump pulse in combination with a wide-field probe pulse, for the spatio-temporal investigation of ultrafast population transport in thin films. The microscope achieves a temporal resolution down to 12 fs and simultaneously provides sub-10 nm spatial accuracy. We demonstrate the capabilities of the microscope by revealing an ultrafast excited-state exciton population transport of up to 32 nm in a thin film of pentacene and by tracking the carrier motion in p-doped silicon. The use of few-cycle optical excitation pulses enables impulsive stimulated Raman micro-spectroscopy, which is used for in-situ verification of the chemical identity in the 100 - 2000 cm-1 spectral window. Our methodology bridges the gap between optical microscopy and spectroscopy allowing for the study of ultrafast transport properties down to the nanometer length scale.