Double Heterostructures for Monolayer Materials with Record Quantum Efficiency

Abstract 2D semiconductor materials have shown great potential and advantages for a wide variety of optoelectronic devices, especially compact and integrated light‐emitting diodes (LEDs) and lasers. However, the lack of a type‐I double‐heterostructure has severely hindered the development of efficient LEDs and lasers based on 2D materials. In this article, a lateral double‐heterostructure is proposed based on a single type‐I heterostructure composed of multilayer WSe 2 and monolayer MoTe 2 with double back‐gates. This design synergizes the high mobility of the multilayer and the direct bandgap of the monolayer: carrier injection and transport are facilitated in the WSe 2 barrier layer, while they are transferred and confined in the MoTe 2 well layer for efficient radiative recombination through type‐I band alignment. Therefore, the double‐heterostructure reaches an external quantum efficiency of 1% level, a new record for p‐n junctions based on transition metal dichalcogenides. Additionally, the heterostructure device achieves a 40‐fold enhancement of the maximum electroluminescent intensity and a 24‐fold enhancement of power efficiency compared with the single monolayer MoTe 2 counterpart at room temperature. This promising strategy can also be extended to other 2D‐semiconductor LEDs and could bring 2D‐materials devices into practical applications of micro‐LED displays, electrically injected 2D‐materials lasers, and silicon‐based on‐chip light sources.