Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures.
Strongly bound excitons confined in two-dimensional (2D) semiconductors are dipoles with a perfect in-plane orientation. In a vertical stack of semiconducting 2D crystals, such in-plane excitonic dipoles are expected to efficiently couple across van der Waals gap due to strong interlayer Coulomb interaction and exchange their energy. However, previous studies on heterobilayers of group 6 transition metal dichalcogenides (TMDs) found that the exciton decay dynamics is dominated by interlayer charge transfer (CT) processes. Here, we report an experimental observation of fast interlayer energy transfer (ET) in MoSe2/WS2 heterostructures using photoluminescence excitation (PLE) spectroscopy. The temperature dependence of the transfer rates suggests that the ET is Förster-type involving excitons in the WS2 layer resonantly exciting higher-order excitons in the MoSe2 layer. The estimated ET time of the order of 1 ps is among the fastest compared to those reported for other nanostructure hybrid systems such as carbon nanotube bundles. Efficient ET in these systems offers prospects for optical amplification and energy harvesting through intelligent layer engineering.
Institute of Advanced Energy, Kyoto University , Gokasho, Uji, Kyoto 611-0011, Japan.|Department of Applied Physics, Waseda University , 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan.|Department of Applied Physics, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Daichi
D
Kozawa
Department of Physics, National University of Singapore , 2 Science Drive 3, 117551, Singapore.|Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, 117546, Singapore.
Alexandra
A
Carvalho
Department of Physics, National University of Singapore , 2 Science Drive 3, 117551, Singapore.|Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, 117546, Singapore.
Ivan
I
Verzhbitskiy
Department of Physics, National University of Singapore , 2 Science Drive 3, 117551, Singapore.|Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, 117546, Singapore.
Francesco
F
Giustiniano
Institute of Advanced Energy, Kyoto University , Gokasho, Uji, Kyoto 611-0011, Japan.|PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
Yuhei
Y
Miyauchi
Institute of Advanced Energy, Kyoto University , Gokasho, Uji, Kyoto 611-0011, Japan.
Shinichiro
S
Mouri
Department of Physics, National University of Singapore , 2 Science Drive 3, 117551, Singapore.|Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, 117546, Singapore.
A H
AH
Castro Neto
Institute of Advanced Energy, Kyoto University , Gokasho, Uji, Kyoto 611-0011, Japan.
Kazunari
K
Matsuda
Department of Physics, National University of Singapore , 2 Science Drive 3, 117551, Singapore.|Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, 117546, Singapore.|Department of Chemistry, National University of Singapore , 3 Science Drive 3, 117543, Singapore.
Goki
G
Eda
Two-dimensional crystal; energy transfer; heterostructure; photophysics; transition metal dichalcogenide