Observation of a giant two-dimensional band-piezoelectric effect on biaxial-strained graphene

Abstract

Piezoelectric materials used in the development of nanoscale mechanical sensors, actuators and energy harvesters have received much attention. More recently, devices made of graphene are of particular interest because of graphene's intriguing electronic and mechanical properties. Intrinsic graphene has long been considered devoid of the piezoelectric effect, although flexoelectricity has been exploited to demonstrate piezoelectricity in functionalized graphene and graphene nanoribbons. The perceived lack of this property has restricted graphene's use in nanoelectromechanical systems (NEMS) for electromechanical coupling purposes. Here an unprecedented two-dimensional (2D) piezoelectric effect on a strained/unstrained graphene junction is reported. In stark contrast to the bulk piezoelectric effect that results from the occurrence of electric dipole moments in solids, the 2D piezoelectric effect arises from the charge transfer along a work function gradient introduced by the biaxial-strainengineered band structure. The observed effect, termed the band-piezoelectric effect, exhibits an enormous magnitude due to the ultrathin structure of graphene. On the basis of the band-piezoelectric effect, a graphene nanogenerator and a pressure gauge were fabricated. The results not only provide a versatile NEMS platform for sensing, actuating and energy harvesting, but also pave the way for efficiently modulating graphene via strain engineering.

The memristive behavior of non-uniform strained carbon nanotubes

“…The cause of surface potentials at the nanotube tops may be the non-uniform elastic strain and piezoelectric effect [6]. …”

“…Previously, we have experimentally shown that vertically aligned CNTs exhibit a memristive switching associated with their strain and polarization [1][2][3]. Analysis of the literature [4][5][6] has shown that non-uniform strain in carbon nanostructures can lead to the appearance of a piezoelectric effect and the corresponding internal electric field in them. We put forward a proposal that the non-uniform strain of the CNT acts as an additional source of resistance which depends on the value of the current flowing.…”

Recent Progress in the Growth and Applications of Graphene as a Smart Material: A Review

“…This is a nanoscale new phenomenon and lacking a direct bulk analog (Luk'yanchuk et al, 2015). This new phenomenon has provided room for practical approach toward manipulation and dynamic control different concerns in nanodevices, such as optical, chemical, and electronic.…”

“…This new phenomenon has provided room for practical approach toward manipulation and dynamic control different concerns in nanodevices, such as optical, chemical, and electronic. Luk'yanchuk et al (2015) have reported an extraordinary two dimensional piezoelectric effect, both on a strained and unstrained graphene junction. Interestingly, it has been formally attested that this 2D piezo effect is a direct consequence of the difference in the two work functions (of the two type of graphene) and hence to the charge transfer occurring from the biaxial strain when putting the two graphene types together (i.e., bend band structure).…”

Piezoelectricity of Functionalized Graphene: A Quantum-Mechanical Rationalization

“…However, its inversion center can be broken and piezoelectricity engineered by several means including adsorption, hole creation, application of biaxial strain, chemical doping, etc. [16][17][18][19][20][21] A large out-of-plane piezoelectric response has recently been measured for a graphene single layer as deposited on a SiO 2 substrate. 20 Among other strategies to induce a piezoelectric response in graphene, chemical doping seems the most promising as it already represents an effective experimental mean for tuning its structural and electronic properties.…”