A Time Domain Ab Initio Insights into Excited-State Carrier Dynamics and Tunable Electronic Properties of 2D WSi₂N₄...

In this work, we take WSi₂N₄ as an example and systematically evaluate its properties across six different stacking configurations using density functional theory (DFT) analysis. The AB stacking is identified as the most thermodynamically favorable, and its unique built-in electric field characteristics are beneficial for enhancing photocatalytic water splitting reactions. The stacking-induced interlayer polarization regulates the electronic properties of photoexcited carriers and significantly suppresses the electron-hole recombination. Under the calculations of the excited-state nonadiabatic dynamics, four electric states include valence band maximum (VBM) and conduction band maximum (CBM) of the upper and lower layers of stacked WSi₂N₄, and three possible de-excitation pathways were identified. Confirming a long excited-state lifetime of 1.65 ns under the de-excitation path of channel ③ in AB-stacked WSi₂N₄, significantly longer than the other two de-excitation paths, and indicating the AB-stacked WSi₂N₄ is a typical type-II band alignment rather than a Z-scheme band alignment.