Visualization of Surface Charge Carrier Diffusion Lengths in Different Perovskite Crystal Orientations Using 4D Electron Imaging
AuthorsNughays, Razan O.
Fatayer, Shadi P.
Mohammed, Omar F.
KAUST DepartmentAdvanced Membranes and Porous Materials Center Division of Physical Science and Engineering King Abdullah University of Science and Technology Thuwal 23955–6900 Saudi Arabia
KAUST Solar Center King Abdullah University of Science and Technology Thuwal 23955–9600 Saudi Arabia
KAUST Catalysis Center Division of Physical Sciences and Engineering King Abdullah University of Science and Technology Thuwal 23955–6900 Saudi Arabia
KAUST Solar Center (KSC)
Physical Science and Engineering (PSE) Division
KAUST Catalysis Center (KCC)
Material Science and Engineering Program
Chemical Science Program
Advanced Membranes and Porous Materials Research Center
Embargo End Date2024-03-20
Permanent link to this recordhttp://hdl.handle.net/10754/690520
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AbstractUnderstanding charge carrier dynamics on the surface of materials at the nanometer and femtosecond scales is one of the key elements to optimizing the performance of light-conversion devices, including solar cells. Unfortunately, most of the pump-probe characterization techniques are surface-insensitive and obtain information from the bulk due to the large penetration depth of the pulses. However, ultrafast scanning electron microscopy (USEM) is superior in visualizing carrier dynamics at the surface with high spatial-temporal resolution. Here, the authors successfully used USEM to uncover the tremendous effect of surface orientations and termination on the charge carrier of MAPbI3 perovskite single crystals. Time-resolved secondary electrons snapshots and density functional theory calculations clearly demonstrate that charge carrier diffusion, surface trap density, surface work function, and carrier concentration are strongly facet-dependent. The results display a diffusion length of 22 micrometers within 6.0 nanoseconds along (001) orientation. While (100) facet forms defect states that prevent carrier diffusion and shows an increase in the surface work function leading to dark contrast and fast charge carrier recombination. These findings provide a new key component to optimizing the surface of perovskites, thus paving the way for even more efficient and stable solar-cell devices based on perovskite single crystals.
CitationNughays, R. O., Yang, C., Nematulloev, S., Yin, J., Harrison, G. T., Zhao, J., Fatayer, S., Bakr, O. M., & Mohammed, O. F. (2023). Visualization of Surface Charge Carrier Diffusion Lengths in Different Perovskite Crystal Orientations Using 4D Electron Imaging. Advanced Optical Materials, 2300190. Portico. https://doi.org/10.1002/adom.202300190
SponsorsThis work was supported by King Abdullah University of Science and Technology (KAUST).
JournalAdvanced Optical Materials