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24 February 2020 Room-temperature multi-phonon upconversion photoluminescence in monolayer semiconductor WS2
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Photon upconversion, a step toward laser cooling of solids, is an anti-Stokes process in which an absorption of a photon leads to a reemission of a photon at energy higher than the excitation energy. Here, we demonstrate room temperature upconversion photoluminescence process in a monolayer semiconductor WS2, with energy gain up to 150 meV. We attribute this process to transitions involving trions (T) and many phonons and free exciton complexes (X). We show that the energy gain significantly depends on the temperature. In order to gain insight into the temperature dependence of the mechanism of the upconverted emission, we combine the normal and upconverted photoluminescence of the monolayer WS2 at low, intermediate and high temperatures. At 7 K the energy gain of upconversion emission amounts about 40 meV, which is comparable with the energy difference between the X and T emission lines and also nearly resonates with the energy of one optical phonon (A’1 or E’). This suggests that at low temperature the upconversion process is related to the coupling between the T and X states mediated by one optical phonon. The higher energy gain of ~60 meV at 70 K suggests that more than one phonon is involved in the upconversion process.
Conference Presentation
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. Jadczak, L. Bryja, J. Kutrowska-Girzycka, P. Kapuściński, M. Bieniek, Y. S. Huang, and P. Hawrylak "Room-temperature multi-phonon upconversion photoluminescence in monolayer semiconductor WS2", Proc. SPIE 11298, Photonic Heat Engines: Science and Applications II, 112980K (24 February 2020);


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