Date/Time: 04-05-2018 - Thursday - 05:00 PM - 07:00 PM
Md Farhadul Haque1 Michael Cai Wang1 Chullhee Cho1 SungWoo Nam1

1, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States

Strain gradient or electric field gradient induced electromechanical response, flexoelectricity, has gained attention owing to its pervasiveness over piezoelectricity. It is present in any dielectric material, whereas piezoelectricity only present in materials with no inversion symmetry. Furthermore, the ease of applying strain gradients at nanoscale without mechanical failure has enabled new opportunities in flexoelectricity based micro or nano electro-mechanical systems. However, inducing flexoelectric effects in two-dimensional materials by inducing strain gradients, especially using substrate wrinkling, has not been investigated. In this presentation, we introduce topography induced tunable flexoelectricity in mono-layer MoS2. The effective out of plane piezoelectric coefficient (d33) of mono-layer MoS2 has been investigated on substrates with controlled topographies, flat and wrinkled, using piezoresponse force microscopy. We observed that the deterministically introduced wrinkles exhibit out of plane electromechanical response on mono-layer MoS2. Since mono-layer MoS2 does not possess out of plane piezoelectric response, our findings are attributed to the converse flexoelectric effect. The induced wrinkles facilitate electric field gradient, thus exhibit out of plane electromechanical response from MoS2 mono-layers. We believe our results on characterizing and tuning the out of plane electromechanical response of wrinkled transition metal dichalcogenide structures can lead to advanced micro and nanoscale actuators and sensors based on flexoelectricity.

Meeting Program

5:00 PM–7:00 PM Apr 5, 2018

PCC North, 300 Level, Exhibit Hall C-E