Nature of the carrier dynamics and contrast formation on the photoactive material surfaces: Insight from ultrafast imaging to DFT calculations

Sarvarkhodzha Nematulloev; Razan O Nughays; Saidkhodzha Nematulloev; Simil Thomas; Dipti R Naphade; Thomas Anthopoulos; Osman M Bakr; Husam N Alshareef; Omar F Mohammed

doi:10.1063/5.0232253

Nature of the carrier dynamics and contrast formation on the photoactive material surfaces: Insight from ultrafast imaging to DFT calculations

J Chem Phys. 2024 Dec 21;161(23):234702. doi: 10.1063/5.0232253.

Authors

Sarvarkhodzha Nematulloev¹, Razan O Nughays¹, Saidkhodzha Nematulloev², Simil Thomas¹, Dipti R Naphade³, Thomas Anthopoulos³, Osman M Bakr², Husam N Alshareef⁴, Omar F Mohammed^{1

2}

Affiliations

¹ Advanced Membranes and Porous Materials Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.
² KAUST Catalysis Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.
³ KAUST Solar Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.
⁴ Materials Science and Engineering, Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.

PMID: 39679511
DOI: 10.1063/5.0232253

Abstract

Precise material design and surface engineering play a crucial role in enhancing the performance of optoelectronic devices. These efforts are undertaken to particularly control the optoelectronic properties and regulate charge carrier dynamics at the surface and interface. In this study, we used ultrafast scanning electron microscopy (USEM), which is a powerful and highly sensitive surface tool that provides unique information about the photoactive charge dynamics of material surfaces selectively and spontaneously in real time and space in high spatial and temporal resolution. Here, time-resolved images of CdTe (110), CdSe (100), GaAs (110), and other semiconductors revealed that the presence of oxide layers on the surface of materials leads to an increase in the work function (WF) and trap state densities upon optical excitation, leading to the formation of dark image contrast in USEM experiments. These findings were further supported by ab initio calculations, which confirmed the reliability of the observed changes in the excited surface WFs. Besides enhancing our understanding of surface charge dynamics, it also offers valuable insights into manipulating these properties. This study paves the way for precise control and the potential to design highly efficient light-harvesting devices.

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