Photophysics, Excitons, Quantum Materials, Ultrafast Spectroscopy
Summary: We are interested in photophysics in nano, molecular, and hybrid semiconductors and interfaces. We focus on dynamics of quasiparticles (excitons, polarons, polaritons, etc.) and their many-body interactions. These interactions are important to a range of optoelectronic processes, such as solar energy conversion, light emission, and polariton condensation. We employ state-of-the-art experimental techniques, including, among others, time-resolved photoemission spectroscopy, femtosecond nonlinear optical spectroscopies, transient absorption and emission spectroscopies, and two-dimensional spectroscopies. As examples, recent discoveries in our lab revealed how dynamic screening and large polaron formation can make lead halide perovskite defect tolerant, how excitons at van der Waals 2D semiconductor interfaces undergo phase transitions, and how cavity exciton polariton condensates in anisotropic semiconductors become excellent quantum simulators of many-body spin-orbit interactions. Our group is part of the DOE Energy Frontier Research Center (EFRC) on Programmable Quantum Materials and part of the NSF Materials Research Science and Engineering Center (MRSEC) for Precision-Assembled Quantum Materials.
Michael S. Spencer, Yongping Fu, Andrew P. Schlaus, Doyk Hwang, Yanan Dai, Matthew D. Smith, Daniel R. Gamelin, X.-Y. Zhu, “Spin-Orbit-Coupled Exciton-Polariton Condensates in Lead Halide Perovskites,” Science Adv, 2021, 7, eabj7667.
Nathan P. Wilson, Kihong Lee, John Cenker, Kaichen Xie, Avalon H. Dismukes, Evan J. Telford, Jordan Fonseca, Shivesh Sivakumar, Cory Dean, Ting Cao, Xavier Roy, Xiaodong Xu, X.-Y. Zhu, “Interlayer Electronic Coupling on demand in a 2D Magnetic Semiconductor,” Nature Mater. 2021, 20, 1657-1662.
Fang Liu, Wenjing Wu, Yusong Bai, Sang Hoon Chae, Qiuyang Li, Jue Wang, James Hone, X.-Y. Zhu, “Disassembling 2D van der Waals Crystals into Macroscopic Monolayers and Reassembling into Artificial Lattices,” Science 2020, 367, 903-906.
Yusong Bai, Lin Zhou, Jue Wang, Wenjing Wu, Leo McGilly, Dorri Halbertal, Chiu Fan B. Lo, Fang Liu, Jenny Ardelean, Pasqual Rivera, Nathan R. Finney, Xuchen Yang, Dmitri N. Basov, Wang Yao, Xiaodong Xu, James Hone, Abhay Pasupathy, X.-Y. Zhu. “Excitons in strain-induced one-dimensional moiré potentials at transition-metal dichalcogenide heterojunctions,” Nature Mater. 2020, 19, 1068-1073.
Jue Wang, Jenny Ardelean, Yusong Bai, Alexander Steinhoff, Matthias Florian, Frank Jahnke, Xiaodong Xu, Mack Kira, James Hone, X.-Y. Zhu, “Optical generation of high carrier densities in 2D semiconductor hetero-bilayers,” Science Adv. 2019, 5, aax0145.
Andrew P. Schlaus, Michael S. Spencer, Kiyoshi Miyata, Fang Liu, Xiaoxia Wang, Ipshita Datta, Michal Lipson, Anlian Pan, X-Y. Zhu, “How lasing happens in CsPbBr3 perovskite nanowires,” Nature Comm. 2019, 10, 265.
Kiyoshi Miyata, X.-Y. Zhu, “Ferroelectric large polarons,” Nature Mater. 2018, 17, 379-381.
Nicholas R. Monahan, Dezheng Sun, H. Tamura, Kristopher W. Williams, Bolei Xu, Yu Zhong, Bharat Kumar, Colin Nuckolls, Avetik R. Harutyunyan, Gugang Chen, Hai-Lung Dai, D. Beljonne, Yi Rao, X.-Y. Zhu, “Dynamics of the triplet pair state reveals the likely co-existence of coherent and incoherent singlet fission in crystalline hexacene,” Nature Chem. 2017, 9, 341-346.
Kiyoshi Miyata, Daniele Meggiolaro, M. Tuan Trinh, Prakriti P. Joshi, Edoardo Mosconi, Skyler Jones, Filippo De Angelis,X.-Y. Zhu, “Large polarons in lead halide perovskites,” Science Adv. 2017, 3, e1701217.
M. Tuan Trinh, Andrew Pinkard, Andrew B. Pun, Samuel N. Sanders, Elango Kumarasamy, Matthew Y. Sfeir, Luis M. Campos, Xavier Roy, X.-Y. Zhu, “Distinct properties of the triplet pair state from singlet fission,” Science Adv. 2017, 3, e1700241.
Gregory D. Scholes, Graham R. Fleming, Lin X. Chen, Alán Aspuru-Guzik, Andreas Buchleitner, David F. Coker, Gregory S. Engel, Rienk van Grondelle, Akihito Ishizaki, David M. Jonas, Jeff S. Lundeen, James K. McCusker, Shaul Mukamel, Jennifer P. Ogilvie, Alexandra Olaya-Castro, Mark A. Ratner, Frank C. Spano, K. Birgitta Whaley, X.-Y. Zhu, “Utilizing Coherence to Enhance Function in Chemical and Biophysical Systems” Nature, 2017, 543, 647-656.
Haiming Zhu, Kiyoshi Miyata, Yongping Fu, Jue Wang, Prakriti P. Joshi, Daniel Niesner, Kristopher J. Williams, Song Jin, X.-Y. Zhu, “Screening in crystalline liquids protects energetic carriers in hybrid perovskites,” Science, 2016, 353, 1409-1413.
Haiming Zhu, Yongping Fu, Fei Meng, Xiaoxi Wu, Zizhou Gong, Qi Ding, Martin V. Gustafsson, M. Tuan Trinh, Song Jin, X.-Y. Zhu, “Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors,” Nature Mater. 2015, 14, 636-642.