Enhanced Piezoelectric Effect Derived from Grain Boundary in MoS₂ Monolayers

Abstract

Recent discovery of piezoelectricity existed in two-dimensional (2D) layered materials represents a key milestone for flexible electronics, miniaturized and wearable devices. However, the so far reported piezoelectricity in these 2D layered materials is too weak to be used for any practical applications. In this work, we discovered that grain boundaries (GBs) in monolayer MoS 2 can significantly enhance its piezoelectric property. The output power of piezoelectric devices made of the butterflyshaped monolayer MoS 2 was improved about 50% by the GB induced piezoelectric effect. The enhanced piezoelectricity is attributed to the additional piezoelectric effect induced by the existence of deformable GBs which can promote polarization and generates spontaneous polarization with different piezoelectric coefficients along with various directions. We further made a flexible piezoelectric device based on the 2D MoS 2 with the GBs and demonstrated its potential application in self-powered precision sensors for in-situ detecting pressure changes in human blood for the health monitoring.

Recent Advances in Strain-Induced Piezoelectric and Piezoresistive Effect-Engineered 2D Semiconductors for Adaptive Electronics and Optoelectronics

“…An increasing output piezoelectric current was investigated with the increase in strain rate. Interestingly, Dai et al [ 221 ] found that grain boundaries in monolayer MoS 2 can significantly enhance its piezoelectric property. The output power of piezoelectric nanogenerator made of the CVD-grown butterfly-shaped monolayer MoS 2 was 50% higher than the device made of triangular sample.…”

Cross‐Substitution Promoted Ultrawide Bandgap up to 4.5 eV in a 2D Semiconductor: Gallium Thiophosphate

“…Recently, the emergence of photodetectors based on 2D materials has opened up an avenue to circumvent the abovementioned dilemma owing to their free surface dangling bonds. [ 13,14 ] In addition, 2D materials usually have atomic thickness, [ 15 ] high specific surface area, [ 16 ] and strong light‐matter interaction, [ 17 ] which can provide high responsivity and photoconductive gain in nanoscale photodetectors. [ 18–22 ] Such 2D materials currently cover a vast range of bandgaps from the terahertz in bilayer graphene, [ 23 ] visible in transition metal dichalcogenides to the ultraviolet in h‐BN and mica.…”

“…[5,12] Recently, the emergence of photodetectors based on 2D materials has opened up an avenue to circumvent the abovementioned dilemma owing to their free surface dangling bonds. [13,14] In addition, 2D materials usually have atomic thickness, [15] high specific surface area, [16] and strong light-matter interaction, [17] which can provide high responsivity and photoconductive gain in nanoscale photodetectors. [18][19][20][21][22] Such 2D materials Exploring 2D ultrawide bandgap semiconductors (UWBSs) will be conductive to the development of next-generation nanodevices, such as deep-ultraviolet photodetectors, single-photon emitters, and high-power flexible electronic devices.…”

Phase Transitions and Water Splitting Applications of 2D Transition Metal Dichalcogenides and Metal Phosphorous Trichalcogenides

“…Piezoelectricity pushes forward 2D TMDs in nanosensor and nanogenerator applications because of their anisotropic piezoelectric coefficient and power output. [ 95 ] As reported by Kim et al., the piezoelectric coefficient of monolayer MoS 2 in the armchair direction is 3.78 pm V −1 , while that in the zigzag direction reaches 1.38 pm V −1 , revealing its anisotropic piezoelectric property and providing a new way harvesting mechanical energy in low power‐consuming devices and self‐powered electronics. [ 96 ] Stacking of 2H‐MoS 2 with even number of layers will eliminate piezoelectricity for centrosymmetry.…”