TY - JOUR
T1 - Real-space imaging of photo-generated surface carrier transport in 2D perovskites
AU - Wang, Lijie
AU - Wu, Wentao
AU - Yang, Jie
AU - Nughays, Razan
AU - Zhou, Yifan
AU - Ugur, Esma
AU - Zhang, Xi
AU - Shao, Bingyao
AU - Wang, Jian Xin
AU - Yin, Jun
AU - De Wolf, Stefaan
AU - Bakr, Osman M.
AU - Mohammed, Omar F.
N1 - Publisher Copyright:
© The Author(s) 2025.
PY - 2025/12
Y1 - 2025/12
N2 - In layered two-dimensional (2D) perovskites, the inorganic perovskite layers sandwiched between cation spacers create quantum well (QW) structures, showing large exciton binding energies that hinder the efficient dissociation of excitons into free carriers. This leads to poor carrier transport properties and low-performance light-conversion-based devices, and the direct understanding of the underlying physics, particularly concerning surface states, remains extremely difficult, if not impossible, due to the challenges in real-time accessibility. Here, we utilized four-dimensional scanning ultrafast electron microscopy (4D-SUEM), a highly sensitive technique for mapping surface carrier diffusion that diverges from those in the bulk and substantially affects material properties. We directly visualize photo-generated carrier transport over both spatial and temporal dimensions on the top surface of 2D perovskites with varying inorganic perovskite layer thicknesses (n = 1, 2, and 3). The results reveal the photo-induced surface carrier diffusion rates of ~30 cm2·s-1 for n = 1, ~180 cm2·s-1 for n = 2, and ~470 cm2·s-1 for n = 3, which are over 20 times larger than bulk. This is because charge carrier transmission channels have much wider distributions on the top surface compared to the bulk, as supported by the Density Functional Theory (DFT) calculations. Finally, our findings represent the demonstration to directly correlate the discrepancies between surface and bulk carrier diffusion behaviors, their relationship with exciton binding energy, and the number of layers in 2D perovskites, providing valuable insights into enhancing the performance of 2D perovskite-based optoelectronic devices through interface engineering.
AB - In layered two-dimensional (2D) perovskites, the inorganic perovskite layers sandwiched between cation spacers create quantum well (QW) structures, showing large exciton binding energies that hinder the efficient dissociation of excitons into free carriers. This leads to poor carrier transport properties and low-performance light-conversion-based devices, and the direct understanding of the underlying physics, particularly concerning surface states, remains extremely difficult, if not impossible, due to the challenges in real-time accessibility. Here, we utilized four-dimensional scanning ultrafast electron microscopy (4D-SUEM), a highly sensitive technique for mapping surface carrier diffusion that diverges from those in the bulk and substantially affects material properties. We directly visualize photo-generated carrier transport over both spatial and temporal dimensions on the top surface of 2D perovskites with varying inorganic perovskite layer thicknesses (n = 1, 2, and 3). The results reveal the photo-induced surface carrier diffusion rates of ~30 cm2·s-1 for n = 1, ~180 cm2·s-1 for n = 2, and ~470 cm2·s-1 for n = 3, which are over 20 times larger than bulk. This is because charge carrier transmission channels have much wider distributions on the top surface compared to the bulk, as supported by the Density Functional Theory (DFT) calculations. Finally, our findings represent the demonstration to directly correlate the discrepancies between surface and bulk carrier diffusion behaviors, their relationship with exciton binding energy, and the number of layers in 2D perovskites, providing valuable insights into enhancing the performance of 2D perovskite-based optoelectronic devices through interface engineering.
UR - http://www.scopus.com/inward/record.url?scp=105000453201&partnerID=8YFLogxK
U2 - 10.1038/s41377-025-01758-5
DO - 10.1038/s41377-025-01758-5
M3 - Article
C2 - 40102415
AN - SCOPUS:105000453201
SN - 2095-5545
VL - 14
JO - Light: Science and Applications
JF - Light: Science and Applications
IS - 1
M1 - 124
ER -