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Medientyp:
E-Artikel
Titel:
Study on the piezoelectric properties and the mechanism of strain-regulated piezoelectricity in flexible Janus monolayers Cr2X3Y3 (X/Y = Cl, Br, I)
Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>Piezoelectric materials hold significant promise in piezoelectric electronics and piezoelectric optoelectronics. As a new member of this family, the 2D Janus structures characterized by central symmetry breaking have attracted much attention due to the out-of-plane piezoelectric effects. In this work, the mechanical, piezoelectric properties, and the strain regulation mechanism of Juans structure material (Cr<jats:sub>2</jats:sub>X<jats:sub>3</jats:sub>Y<jats:sub>3</jats:sub>, X/Y = Cl, Br, I) are systematically investigated by the first-principles methods. The calculated mechanical properties show that Cr<jats:sub>2</jats:sub>X<jats:sub>3</jats:sub>Y<jats:sub>3</jats:sub> with a lower Young’s modulus of 27.31∼29.76 N m<jats:sup>−1</jats:sup> is more sensitive to applied stresses, theoretically exhibiting exceptional piezoelectric properties. The in-plane piezoelectric coefficients <jats:italic>d</jats:italic>
<jats:sub>11</jats:sub> for Cr<jats:sub>2</jats:sub>Br<jats:sub>3</jats:sub>Cl<jats:sub>3</jats:sub>, Cr<jats:sub>2</jats:sub>I<jats:sub>3</jats:sub>Cl<jats:sub>3,</jats:sub> and Cr<jats:sub>2</jats:sub>I<jats:sub>3</jats:sub>Br<jats:sub>3</jats:sub> are 4.92, 9.89, and 7.86 pm V<jats:sup>−1</jats:sup>, respectively; the out-of-plane piezoelectric coefficients <jats:italic>d</jats:italic>
<jats:sub>31</jats:sub> are 1.13, 2.33, and 1.64 pm V<jats:sup>−1</jats:sup>, respectively. Cr<jats:sub>2</jats:sub>I<jats:sub>3</jats:sub>Cl<jats:sub>3</jats:sub> has the highest values of <jats:italic>d</jats:italic>
<jats:sub>11</jats:sub> and <jats:italic>d</jats:italic>
<jats:sub>31</jats:sub> due to the large electronegativity difference between iodine and chlorine atoms. Based on the analysis, it can be deduced that Cr<jats:sub>2</jats:sub>X<jats:sub>3</jats:sub>Y<jats:sub>3</jats:sub> demonstrates substantial piezoelectric responses in both in- and out-of-plane, with potential strain regulation effects. The <jats:italic>d</jats:italic>
<jats:sub>31</jats:sub> values of Cr<jats:sub>2</jats:sub>I<jats:sub>3</jats:sub>Cl<jats:sub>3</jats:sub> show an approximately linear relationship to strain in the range from −2% to 4% and remain consistently above 2.10 pm V<jats:sup>−1</jats:sup> across a broader range of strain from −4% to 6%, underscoring its robustness to strain. Our study indicates that two-dimensional Janus Cr<jats:sub>2</jats:sub>X<jats:sub>3</jats:sub>Y<jats:sub>3</jats:sub> monolayers would emerge as promising candidates for diverse applications in multifunctional electronic devices.</jats:p>