Mobile technology
When a piezoelectric material is subjected to mechanical stress, it is polarized and acquires a potential difference and electrical charge on its surface. This phenomenon, discovered by the Curie brothers in 1880, has innumerable applications such as the production and detection of sound or the generation of high voltage. In addition, piezoelectricity is at the base of scientific instrumental techniques with atomic resolution, such as tunnel or atomic force microscopes. In all these applications, the piezoelectric material used has dimensions on the macroscopic scale. Nevertheless,
On the fifteenth day of this month, researchers from Columbia University and the Georgia Institute of Technology presented to the world the first sheet of molybdenum disulfide (MoS2) that in 2D format (one of the spatial dimensions is reduced to a few atoms while that the other two remain with macroscopic sizes) presents piezoelectric behavior. Perhaps one of the most surprising issues is that a block of molybdenum disulfide does not exhibit piezoelectric behavior; it is only when an atomic thickness is available, when piezoelectricity manifests itself. These researchers have shown that, by subjecting 2D MoS2 sheets with an odd number of atomic layers to strain-relaxation cycles, an oscillating piezoelectric voltage is produced and electrical current is obtained while nothing is observed if the sheets have an even number of layers (the material is highly polar so an even number of layers cancels the net effect). Under maximum power conditions, a 0.53% deformed monoatomic sheet generates a potential difference of 15 mV for a current of 20 pA (1 pA equivalent to 10-12 A), corresponding to a power generated per unit area 2 mW m-2 and an efficiency of 5.08% in the conversion of mechanical energy into electrical. In addition, in line with the theoretical predictions made, efficiency increases as the thickness decreases and the potential difference changes sign when the deformation direction is rotated 90 °.
When a piezoelectric material is subjected to mechanical stress, it is polarized and acquires a potential difference and electrical charge on its surface. This phenomenon, discovered by the Curie brothers in 1880, has innumerable applications such as the production and detection of sound or the generation of high voltage. In addition, piezoelectricity is at the base of scientific instrumental techniques with atomic resolution, such as tunnel or atomic force microscopes. In all these applications, the piezoelectric material used has dimensions on the macroscopic scale. Nevertheless,
On the fifteenth day of this month, researchers from Columbia University and the Georgia Institute of Technology presented to the world the first sheet of molybdenum disulfide (MoS2) that in 2D format (one of the spatial dimensions is reduced to a few atoms while that the other two remain with macroscopic sizes) presents piezoelectric behavior. Perhaps one of the most surprising issues is that a block of molybdenum disulfide does not exhibit piezoelectric behavior; it is only when an atomic thickness is available, when piezoelectricity manifests itself. These researchers have shown that, by subjecting 2D MoS2 sheets with an odd number of atomic layers to strain-relaxation cycles, an oscillating piezoelectric voltage is produced and electrical current is obtained while nothing is observed if the sheets have an even number of layers (the material is highly polar so an even number of layers cancels the net effect). Under maximum power conditions, a 0.53% deformed monoatomic sheet generates a potential difference of 15 mV for a current of 20 pA (1 pA equivalent to 10-12 A), corresponding to a power generated per unit area 2 mW m-2 and an efficiency of 5.08% in the conversion of mechanical energy into electrical. In addition, in line with the theoretical predictions made, efficiency increases as the thickness decreases and the potential difference changes sign when the deformation direction is rotated 90 °.
