Defect-Induced Ultrafast Nonadiabatic Electron–Hole Recombination Process in PtSe<sub>2</sub> Monolayer
Hongfu Huang, Junhao Peng, Zixuan Li, Huafeng Dong, Le Huang, Minru Wen, Fu‐Gen Wu
Abstract
Defects are inevitable in two-dimensional materials due to the growth condition, which results in many unexpected changes in materials’ properties. Here, we have mainly discussed the nonradiative recombination dynamics of PtSe2 monolayer without/with native point defects. Based on first-principles calculations, a shallow p-type defect state is introduced by a Se antisite, and three n-type defect states with a double-degenerate shallow defect state and a deep defect state are introduced by a Se vacancy. Significantly, these defect states couple strongly to the pristine valence band maximum and lead to the enhancement of the in-plane vibrational Eg mode. Both factors appreciably increase the nonadiabatic coupling, accelerating the electron–hole recombination process. An explanation of PtSe2-based photodetectors with the slow response, compared to conventional devices, is provided by studying this nonradiative transitions process.