The interlayer interaction in layered two-dimensional (2D) materials used to be believed dominated by Van der Waals force. We recently found an emergent type of interlayer interaction, covalent-like quasi-bonding (CLQB) [1, 2], in various 2D materials such as black phosphorus [1, 2], PtS2 [3], PtSe2 [4] and alpha-Te [5]. These materials exhibit strong orbital hybridization between interlayer/interchain atoms around the valence band maximum and conduction band minimum and show a charge transfer between adjacent layers with covalent characteristics. CLQB, a strong interlayer coupling, results in layer-dependent geometric structure, electronic, transport, optical and vibrational properties for many low-dimensional materials, playing an important role in layered engineering.

In addition, we found the competition between interlayer and intralayer interactions results in different molecule-stacking orders in the first and (above) the second layer of 2D molecule (organic) materials, which furthermore introduces diverse geometric, electronic, transport, contact properties into the materials. [6, 7] Constructing different stacking order of 2D molecule materials paves a new way to improve the performance of the organic field-effect transistors (OFETs) and organic displays.


  1. J. Qiao, et al., Nature Communications, 5, 4475 (2014).
  2. Z. Hu, et al., Nanoscale, 8, 2740-2750 (2016).
  3. Y. Zhao, et al., Advanced Materials, 28, 2399–2407 (2016).
  4. Y. Zhao, et al., Advanced Materials, 29, 1604230 (2017).
  5. J. Qiao, et al., Science Bulletin, 63 (3), 159-168 (2018).
  6. D. He, et al., Science Advances, 3, e1701186 (2017).
  7. Y. Zhang, et al., Physical Review Letters, 116,016602 (2016).

Speaker’s Bio

Dr. Qiao Jingsi received her PhD degree in physics from Renmin University of China in July 2018 and then joined the Center for advanced 2D materials of National University of Singapore as a Postdoctoral research fellow. Her research interests cover the field of surface and interface modeling of low-dimensional materials. Her work focuses on theoretical modeling of electronic, optical and vibrational properties of two-dimensional materials using first-principle DFT and GW-BSE calculations. Her findings have been published in Nature Communications, Science Advances, Advanced Materials, Physical Review Letter and other peer-reviewed journals, including 7 ESI highly cited papers and 2 ESI hot papers, and have been cited more than 2000 times.