LIU GROUP @ THU
1. Interface strain engineering of 2-dimensional (2D) van der Waals materials
Interface strain deforms materials or even causes structural failure, and could dramatically modulate the properties of 2D materials and affect their device performance. We probed and controlled the strain-induced dynamic deformation (buckling) and fracture of 2D materials (MoS2, MoTe2, etc.). We developed a universal shear-boundary model to describe the interlayer interactions of 2D materials, and found a unique soliton-wave-like buckling mode in strained MoS2 thin films under high humidity. We also engineered interface geometries to modulate interface strain and realize high-performance actuators and high-sensitivity tactile sensors. These studies of interface strain are very important especially for the applications of 2D materials in harsh environments, where interface stain like thermal strain is very common to fail the materials or devices.
Selected publications:
Nature Communications, 14, 4324 (2023);
Nature Communications, 13, 3898 (2022);
ACS Nano, 16, 14157 (2022);
Advanced Functional Materials, 30, 1909616 (2020)
ACS Nano, 13, 3106 (2019);
Nano Lett., 19, 761 (2019).
2. Interface engineering of 2D materials for high-efficiency smart devices
Hetero-structures or spatially-doped homo-structures are fundamental blocks in modern semiconductor devices. Engineering the hetero-interfaces and homo-interfaces can not only improve the device performance, but enable new functions in devices. We explored novel types of lateral hetero-/homo-structures, such as 2D transition metal chalcogenide (TMD)/oxide (TMO) heterostructures and graded doped 2D TMD materials, to realize high efficiency and multiple functions of smart devices. For example, employing the technique of direct laser writing, we fabricated a variety of TMD/TMO lateral heterostructures, including V5S8/VO2, NbS2/Nb2O5, and MoS2/MoS1-xOy, for high-performance gas sensors, memristors, and synaptic devices.
Selected publications:
Nature Electronics, doi: 10.1038/s41928-023-01056-1 (2023);
Science Advances, 7, eabk3438 (2021);
Advanced Materials, 33, 2102435 (2021);
ACS Nano, 15, 10502 (2021);
ACS Nano, 14, 175 (2020);
Materials Today, 21, 875 (2018) (Invited review);
Nano Letters, 17, 421 (2017).
3. Interface engineering for high-temperature (HT) nanodevices
Emerging applications in artificial intelligence and automotive electronics usually request materials/devices to work at HTs (>125 °C). Nanomaterials including 1D and 2D materals are favorable for high integration of devices but are usually subject to less stability at HTs. The key strategy to address this problem is interface engineering, which can effectively stabilize the entire system and may deliver new functions at HTs. Based on the strategy of interface engineering, we developed HT graphene-buffered electrodes and HT monolayer MoS2 synaptic devices that can work up to 350 °C. We also developed a lightweight, solid tape made of carbon nanotube films that are capable of working at extremely wide range of temperatures (-196°C~1000°C).
Selected publications:
Advanced Materials, 35, 2210735 (2023);
Nature Communications, 13, 3338 (2022);
Nano Lett., 21, 10400 (2021);
Nano Lett., 19, 6756 (2019).