Successful International Mini-Workshop on Energy Material Interfaces Showcases Global Collaboration and Innovation

Dr. Yujin Tong, alongside Ms. Natalie Miladic, orchestrated a successful "International Mini-Workshop on Energy Material Interfaces" at Gutshotel Baron Knyphausen, Eltvilla am Rhein, Germany, from August 14-17. Over 20 scholars from China, Germany, USA, Brazil, and Taiwan actively participated onsite and online, achieving the workshop's goals of knowledge sharing, highlighting emerging trends in energy material interfaces, addressing challenges, and fostering networking for potential collaborations and research partnerships. The event proved to be a hub for cutting-edge research and global collaboration in the fields of energy harvesting, storage, renewable energy systems, and energy conversion technologies.

For more information and pictures go to: https://sites.google.com/view/workship-energ-mater-interface/home

Exciting New Insights into Monolayer Transition Metal Dichalcogenides and Gold Interaction

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Congratulation on Tao’s first PRB paper (Phys. Rev. B 107, 155433)! In this work, we employed azimuthal-dependent sum frequency generation (SFG) spectroscopy to analyze the interaction between monolayer MoS2, a TMDC, and gold surfaces. This was achieved by comparing the second-order nonlinear optical (NLO) response of MoS2 on both Si/SiO2 and gold, with a focus on how the patterns and intensities change with the azimuthal angle and under different polarizations. The study revealed that the interaction between MoS2 and gold significantly alters both the magnitude and symmetry of the NLO response, in contrast to its behavior on Si/SiO2. This finding aligns with prior theoretical studies, emphasizing a strong interaction between monolayer MoS2 and the gold substrate. This research offers a contact-free method to probe substrate-induced changes in the electronic structure of TMDC monolayers. Its implications are far-reaching, particularly in the development of optoelectronic devices, and it opens new avenues for exploring the potential of TMDCs in technological applications.

Innovative Study Unveils New Optical Responses in 2D Semiconductor-Metal Junctions

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In this second piece of work (under review in PRB, preprint is available here 
arXiv:2310.19657), we seek to employ the different symmetries of the responses from metal and TMDC to isolate the optical responses of a MoS2 monolayer in a MoS2/Au junction. The SFG spectra exhibited a linear lineshape without any A or B exciton features. This characteristic was attributed to the strong dielectric screening and substrate-induced doping at the junction. The linear lineshape of the spectra interestingly reflects the constant density of states (DOS) at the band edge of the 2D semiconductor. We were able to extrapolate from their findings to determine the onset of a direct quasiparticle bandgap of approximately 1.65 ± 0.20 eV, indicating a substantial renormalization of the bandgap. This study not only enhances our understanding of the optical responses of 2D semiconductors under extreme screening conditions but also serves as a vital reference for the advancement of 2D semiconductor-based photocatalytic applications.