Publication

Spatiotemporal Observation of Electron-Impact Dynamics in Photovoltaic Materials Using 4D Electron Microscopy

Spatiotemporal Observation of Electron-Impact Dynamics in Photovoltaic Materials Using 4D Electron Microscopy
Basamat S. Shaheen, Jingya Sun, Ding-Shyue Yang, and Omar F. Mohammed
J. Phys. Chem. Lett., 20178, pp 2455–2462
Basamat S. Shaheen, Jingya Sun, Ding-Shyue Yang, Omar F. Mohammed
Photovoltaic materials, Surface dynamics, 4D electron microscopy, electron impact dynamics, energy loss, CdSe thin films
2017
 
Understanding light-triggered charge carrier dynamics near photovoltaic material surfaces and at interfaces has been a key element and one of the major challenges for the development of real-world energy devices. Visualization of such dynamics information can be obtained using the one-of-a-kind methodology of scanning ultrafast electron microscopy (SUEM). Here, we address the fundamental issue of how the thickness of the absorber layer may significantly affect the charge carrier dynamics on material surfaces. Time-resolved snapshots indicate that the dynamics of charge carriers generated by electron impact in the electron‒photon dynamical probing regime is highly sensitive to the thickness of the absorber layer, as demonstrated using CdSe films of different thicknesses as a model system. This finding not only provides the foundation for potential applications of S-UEM to a wide range of devices in the fields of chemical and materials research, but also has impact on the use and interpretation of electron beam-induced current for optimization of photoactive materials in these devices.
DOI: 10.1021/acs.jpclett.7b01116