邀请人：孟胜 研究员（9396）

联系人：王立芬 副研究员（9963）

报告摘要：
We explore the fascinating world of low-dimensional materials, using first-principles calculations and modeling with many-body techniques. We have discovered and characterized the topological phases in GNRs of different widths, edges, and end terminations [1]. The concept has inspired experimental works to engineer the topological interface states determined by topological invariants in GNRs [2]. We further designed a periodically doped GNR structure with tunable topological phases by transverse electric fields, which provides new insights in designing quantum dot qubits with tunable interactions [3]. Magnetism in GNR makes it a promising candidate for spintronic devices, and by using first-principles GW calculations, we have predicted a band splitting phenomenon in the experimentally synthesized nitrogen-doped zigzag GNR, which led to the first experimental verification of magnetism in GNR [4].

On the other hand, we explore the nonradiative recombination mechanism in semiconductors. With my developed first-principles calculation formalism to calculate the rate of a trap-assisted Auger-Meitner (TAAM) process, we have shown that the TAAM process is the key nonradiative recombination mechanism to limit the efficiency in wide-band-gap semiconductor devices such as blue light-emitting diodes [5, 6]. 

[1] Cao, Zhao, and Louie, Phys. Rev. Lett. 119, 076401 (2017).

[2] Rizzo, Veber, Cao, Zhao, Louie, Crommie, and Fischer et al., Nature 560, 204 (2018).  

[3] Zhao, Cao, Louie, Phys. Rev. Lett. 127, 166401 (2021).

[4] Blackwell*, Zhao*, Louie, and Fischer et al., Nature 600, 647 (2021).

[5] Zhao, Turiansky, Alkauskas, and Van de Walle, Phys. Rev. Lett. 131, 056402 (2023).

[6] Zhao, Guan, Turiansky, and Van de Walle, Appl. Phys. Lett. 126, 201106 (2025). 

报告人简介：

Fangzhou Zhao is a Humboldt fellow in Prof. Angel Rubio’s group at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, since 2024. Fangzhou obtained his Ph.D. in Physics at the University of California, Berkeley with Prof. Steven G. Louie in 2021, and he obtained his B.S. degree in Physics from Zhiyuan College, Shanghai Jiao Tong University in 2015. He has been an Elings Prize Postdoctoral Fellow at UC Santa Barbara, from June 2021 to December 2023.

Fangzhou’s graduate work consists of topological electronic and optical properties of quasi-one-dimensional nanomaterials like graphene nanoribbons and carbon conjugated systems, as well as the GW plus Bethe-Salpeter equation formalism to calculate excited state properties of materials. As an Elings postdoc at UCSB, Fangzhou developed a first-principles calculation formalism and code to calculate the rate of trap-assisted Auger-Meitner recombination in semiconductors and was honored with the Corbett Prize at the 32nd International Conference on Defects in Semiconductors and the NERSC High Performance Computing Achievement Award. Fangzhou works on theoretical formalism on exciton-exciton correlations and cavity engineering as a Humboldt fellow. Fangzhou has published papers in top journals such as Nature, Physical Review Letters, Nature Communications, Nano Letters, and Journal of the American Chemical Society.