Electrically Switchable Chiral Light-Emitting Transistor

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Science  17 Apr 2014:
DOI: 10.1126/science.1251329

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Tungsten diselenide (WSe2) and related transition metal dichalcogenides (TMDs) exhibit interesting optoelectronic properties due to their peculiar band structures originating from the valley degree-of-freedom. While the optical generation and detection of valley polarization has been demonstrated, it has been difficult to realize active valley-dependent functions suitable for device applications. We report an electrically switchable circularly polarized light source based on the material’s valley degree-of-freedom. Our WSe2-based ambipolar transistors emit circularly polarized electroluminescence from p-i-n junctions electrostatically formed in transistor channels. This phenomenon can be explained qualitatively by the electron–hole overlap controlled by the in-plane electric field. Our device demonstrates a route to exploit the valley degree-of-freedom, and the possibility to develop a valley-optoelectronics technology.

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