High Anisotropic Optoelectronics in Monolayer Binary M 8 X 12 (M = Mo, W; X = S, Se, Te).

Exploring high performance and excellent ambient stability in two-dimensional (2D) monolayer photoelectric materials is motivated by not only practical applications but also scientific interest. Here, a new 2D monolayer W 8 Se 12 structure is synthesized via in situ electron-beam irradiation on 2D WSe 2 . Moreover, we systematically studied the photoelectric properties of the class of monolayer M 8 X 12 (M = Mo, W; X = S, Se, and Te) materials by first principles. The results indicated that Mo 8 S 12 , Mo 8 Se 12 , W 8 S 12 , and W 8 Se 12 monolayers possess desirable direct band gaps and remarkable anisotropic optical absorption in visible light, while Mo 8 Te 12 and W 8 Te 12 monolayers are metals. Impressively, the monolayer W 8 Se 12 can result in a direct-indirect-metal transition under uniaxial strain. In addition, they show high anisotropic carrier mobilities (up to 10 4 cm 2 V -1 s -1 ), significantly over those of transition-metal dichalcogenides. These new binary monolayer M 8 X 12 structures can effectively broaden the 2D material family and may provide four potential candidates in photoelectric applications.