Fig. 5: Light upconversion in few-layer MoS2, MoSe2, WS2, and WSe2 at T = 80 K. | Nature Communications

Fig. 5: Light upconversion in few-layer MoS2, MoSe2, WS2, and WSe2 at T = 80 K.

From: Efficient light upconversion via resonant exciton-exciton annihilation of dark excitons in few-layer transition metal dichalcogenides

Fig. 5

a Photoluminescence spectrum of 5 L WS2, 3 L MoS2, and 3 L MoSe2 at emission energy ranging from 1.2 to 3.1 eV. The excitation energy (2.33 eV) is denoted as the green arrow. b UPL spectra of 6 L WS2, MoS2, and MoSe2 in contrast to thinner counterparts (3 L WS2, 3 L MoS2, and 4 L MoSe2). The spectra are normalised to the incident power. The excitation energy for each spectrum (2.33 eV for WS2 and MoS2, 1.96 eV for MoSe2) is denoted as the green arrow. c Peak energy of UPL in MoS2 (open), MoSe2 (solid), WS2 (half left), and WSe2 (half up) with the layer thickness ranging from 3 L to 7 L, and thicker than 7 L.

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