In 2014, two-dimensional black phosphorus, widely considered an ideal semiconductor material, was isolated for the first time, generating interest in group-V elements. In the time since, useful stable structures have been identified in phosphorene, arsenene, antimonene and bismuthene. This new paper reports first-principles calculations of the electronic structure and piezoelectric properties of several group-V binary compounds, finding super piezoelectric properties in many of the combinations.

Chen et al. perform first-principles calculations based on density functional theory on what they term the β structure of the compounds. Typically, these compounds have a honeycomb lattice structure known as an alpha structure. However, under physical strain the structure can be deformed into another stable state, the β-phase. The paper presents the characterization of several group-V binary compounds: β-AsP, β-SbN, β-SbP, β-SbAs and β-BiP.

The results show the β-phase materials are all semiconductors with direct band gaps. Furthermore, all of their respective direct band gap properties were predicted to be stable under large strain. With the exception of β-SbN, all compounds were predicted to have piezoelectric coefficients about one order of magnitude higher than other commonly used piezoelectric materials.

Piezoelectric materials convert mechanical energy into electrical energy and thus have wide applications as mechanical stress sensors, actuators, electric field generators and other functional devices. The combination of super piezoelectric and direct band gap properties show that the β-phase compounds may be good candidates for flexible sensors and energy conversion devices in the future.

Source: “A new phase of monolayer group-V binary compounds with direct band gap and giant piezoelectric properties,” Feiyao Chen, Hongxiang Xu, Jianyu Wang, Zhendong Wang, Xiaoqing Liu, Yan Lu, and Li Wang, Journal of Applied Physics (2019). The article can be accessed at