11 a.m. - noon Location: RL 3.204
ABSTRACT: Nanostructures have attracted growing research attention to improve the performance of optoelectronic devices, including photodetectors, solar cells, and light emitting diodes. We prepared P3HT-coated Si-nanopillar (NP) arrays and studied spatial distribution of the surface photovoltage (SPV) in the samples using Kevin probe force microscopy. The Si-NPs with high aspect ratio exhibited broadband and omnidirectional antireflection effects. Furthermore, large SPV values appeared in the P3HT layers near the Si NPs under illumination of visible light. The optical resonance strongly concentrated incident light in the Si NPs due to the graded refractive index and Mie scattering, which increased the local density of the photo-generated carriers near the NPs. We also studied the optical characteristics of 2D MoS2 layers conformally coated on 3D Si-based nanostructured substrates. The photoluminescence and Raman intensities of the MoS2 monolayers on SiO2 nanocones (NCs) are much greater than those on Si NCs. The weak light confinement in low refractive index SiO2 NC led to a large surface electric field intensity and increased the absorption of the MoS2 monolayers. The photocurrent in MoS2 monolayers on nanorugged substrates showed drastic increase compared with those on planar counterparts, which indicated the suppressed recombination loss induced by local strain. Our works have demonstrated that the Si-based nanostructures, fabricated by well-established fabrication techniques, are very helpful to improve not only the light trapping capability but also the carrier collection efficiency of the thin active layers grown on them.
 E. Kim et al., Sci. Rep. 6, 29472 (2016).
 E. Kim et al., Nanoscale 10, 18920 (2018).
 T. K. Nguyen et al., ACS Appl. Mater. Interfaces DOI: 10.1021/acsami.8b15673 (2018).
BIO: Dr. Dong-Wook Kim earned his B.S. (’95), M.S.(’97), and Ph.D.(’01) in Physics from Seoul National University in Korea. He has worked as a senior researcher at the Samsung Advanced Institute of Technology (’01-’05), a visiting scientist at the University of California, San Diego (’03-’05), and an assistant professor at Hanyang University at Ansan (’05-’08). In 2008, he joined in Department of Physics at Ewha Womans University in Korea as a faculty member. He is a member of editorial board of Scientific Reports, Current Applied Physics, and Journal of the Korean Physical Society. Selected honors include Outstanding Research Award from Applied Physics Division of Korean Physical Society (2018) and Outstanding Research Achievement Award from Ewha Womans University (2015).
Jennifer Alsbury, 972-883-5754
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