Two-dimensional hydrogenated/fluorinated graphyne/graphyne-like BN van der Waals heterostructures and their potential application in ultraviolet photodetection: A theoretical prediction

ga1 • Surface atom functionalization is one of the effective approaches to modifying electronic structures of carbon-based two-dimensional materials. • Type-I/type-II band alignment transition occurred in Gyne/BNyne under hydrogenation and fluorination. • BNyne serves as acceptor and donor in H-Gyne/BNyne and F-Gyne/BNyne, respectively. • Both the H-Gyne/BNyne and F-Gyne/BNyne vdWHs show significant optical absorption in the range of UV light. • The X-Gyne/BNyne vdWHs may be an excellent candidate for visible-blind, solar-blind, or vacuum UV photodetectors. Constructing van der Waals heterostructures (vdWHs) with staggered type-II band alignment, thereby prompting the charge separation rate and enhancing the photoresponsivity, is an effective way to boost the photoelectric performance of photodetectors. However, suitable vdWHs for ultraviolet (UV) photodetection remain unexplored owing to the few two-dimensional (2D) wide band gap semiconductors. Herein, based on the first-principles calculation, we proposed a novel X atom functionalized-graphyne/graphyne-like BN (X-Gyne/BNyne) vdWHs for promising UV photodetectors. Both the hydrogenated (H-) and fluorinated (F-) Gyne are not only energetically and thermodynamically stable, but possess wide band gap characteristics due to the destruction of π bonds. The H-Gyne/BNyne vdWHs with high adatom coverage and the F-Gyne/BNyne vdWHs exhibit type-II band alignment with large band offset and dominant UV optical absorption. Intriguingly, the BNyne serves as electron acceptor and electron donator in H-Gyne/BNyne and F-Gyne/BNyne vdWHs, respectively. Furthermore, the photoelectric conversion process that may be involved in the X-Gyne/BNyne-based prototype UV photodetector is elucidated. Our results will greatly enlarge the promising application of the Gyne-based vdWHs in the photoelectronic industry and further stimulate the research enthusiasm on other vdWHs that the charming electronic properties can be modulated by various general methods.