Coupled relaxation channels of excitons in monolayer MoSe2.

Using ultrafast degenerate pump-probe spectroscopy, we have investigated the ultrafast exciton dynamics of monolayer MoSe2 at different pump fluences. The exciton-exciton annihilation, typically occurring tens of picoseconds after pump excitation, has been found to have a substantial correlation with the initial relaxation process dominated by the defect trapping of excitons. A new exciton-exciton annihilation model has been proposed by introducing a coupling term that accounts for the initial relaxation contribution. This coupling term can be tuned by varying the pump excitation intensity and at a high intensity it vanishes due to the full occupation of the defect states. At the same time, the final electron-hole recombination is found to be affected by the heat accumulation effect originating from the high intensity pump pulses.

Citation

Bo Liu, Yuze Meng, Xuezhong Ruan, Fengqiu Wang, Wengqin Liu, Fengqi Song, Xuefeng Wang, Jing Wu, Liang He, Rong Zhang, Yongbing Xu. Coupled relaxation channels of excitons in monolayer MoSe2. Nanoscale. 2017 Nov 22

PMID: 29164206

search → result