Effects of vacancy defects on the electronic, mechanical, and optical properties of penta-B2C4

The synthesis of two-dimensional (2D) pentagonal structures has sparked interest in further research on this class of materials. Here, the effects of intrinsic point vacancy defects on the electronic, mechanical, and optical properties of Penta-B2C4 were systematically investigated. The research indicates that three types of point vacancy defects (VB, VC and VBC) cause varying degrees of upward shift in the Fermi level of Penta-B2C4, ultimately leading to its transformation from p-type semiconductor to n-type semiconductor. The VB defect disrupts the mechanical stability of Penta-B2C4 while VC and VBC defects still maintain excellent mechanical properties, exhibiting flexibility even superior to graphene. The three vacancy defects also improve the visible optical absorption properties of Penta-B2C4, but the reflectance and refractive index in the same environment decrease. The research findings provide theoretical support for the application of Penta-B2C4 in flexible devices, mechanical engineering, and optoelectronic devices.