Theoretical design and discovery of two‐dimensional materials for next‐generation flexible piezotronics and energy conversion

Abstract

Two‐dimensional (2D) materials are at the epicenter of the current nanotechnology research for its intriguing properties. It has the advantage of high flexibility, high surface to volume ratio, robust mechanical strength and are stackable in contrary to bulk materials. Piezoelectric effect is exploited in 2D layered nanomaterials with broken inversion symmetry and non‐zero band gap for applications in energy harvesting and energy conversion. Density functional theory (DFT) is a powerful tool to predict the piezoelectric properties of 2D materials. This mini review emphasizes the importance and discusses the challenges of different methods within DFT‐based framework to compute piezoelectric properties. Recent simulation works of piezoelectric engineering in novel 2D semiconductors for in‐plane and out‐of‐plane piezoelectricity are reviewed. Various controlling parameters and techniques for piezoelectric effect are also discussed. Theoretical predictions pave the path for experimental exploration of 2D materials exhibiting strong piezoelectric properties and to replace the commercially used lead‐based toxic materials in future devices.

Engineering piezoelectricity at vdW interfaces of quasi-1D chains in 2D Tellurene

“…These stackings have band gaps in the range of 0.70 eV-0.87 eV where AA ′ and AB ′′ attain direct band gaps while AA ′′ and AB acquire indirect band gaps. Thus, piezoelectricity coefficients can be determined for the bilayers using the expression [4,51],…”

“…As AA ′ stacking exhibits highest piezoelectric stress coefficient, piezoelectric strain coefficient d 2D 22 is evaluated using the relation, e ik = ∑ 6 j d ij C jk [51]. The resulting strain coefficient is equivalent to −351.34 pm V −1 , corresponding to a voltage coefficient (g ij = d ij /ϵ 0 ϵ ii [58], where ϵ represents 1.93 [54] the dielectric constant (ESI)) of 1.2 Vm N −1 .…”

Advances in Piezoelectric Two-Dimensional Materials for Energy Harvesting

“…Piezoelectric materials can replace batteries by exploiting energy from the environment for the design of self-powered devices with power consumption in the range of microwatts or milliwatts [36]. These materials offer an environmentally friendly alternative by avoiding the disposal of waste batteries that have not been manufactured and recycled with green technologies.…”