Size-dependent shape characteristics of 2D crystal blisters

Dear friends, I want to share our recent work on the shape characteristics of 2D crystal blisters. Micro- and nano-sized blisters can form spontaneously when two-dimensional (2D) crystals are transferred onto substrates because liquid molecules that are initially adsorbed on 2D material and substrate surfaces can be squeezed and trapped by interfacial forces. On the one hand, blisters are undesirable in 2D material devices as they impede charge/photon/phonon transport across the interface, so various means were developed to eliminate interfacial blisters. On the other hand, mechanics analysis has elucidated that the blister morphology is a good indicator of the interfacial properties of 2D crystals, such as adhesion. Furthermore, the inhomogeneous strain distributions and the rich surface topographies of 2D crystal blisters can be leveraged for optimizing luminescence and exciton transport in 2D crystals, as well as designing mechanical sensors, microlenses, and more. In this work, we use a combination of experiments, continuum theories, and coarse-grained molecular dynamics (CGMD) simulations to investigate the shape characteristics of spontaneously formed blisters under 2D crystals with heights ranging from a few ångströms to tens of nanometers. We show three distinct regimes in which the height-to-radius ratios (i.e., aspect ratios) of 2D crystal blisters are size-independent, rough linearly proportional, and inversely proportional to the blister radius. We reveal that the blister shape characteristics are governed by three factors: the 2D crystal elasticity, the interfacial interactions, and the phases of confined substances. The characteristic length scales (to which comparing the blister height or radius can define the boundary between these different regimes) are also discussed. We also provide the criteria of the plate-to-membrane theory transition, the Griffith-to-vdW interface transition, and the liquid-to-monolayer-lattice transition regarding the phase of interface substances as practical guidelines for choosing the correct models for 2D crystal blisters.

The publisher link is here; A copy of the manuscript is also available from ResearchGate. 

Thanks for your attention.

Sincerely,

Yifan