Long-lived interlayer excitons (IXs) in van der Waals heterostructures (HSs) stacked by monolayer transition metal dichalcogenides (TMDs) carry valley-polarized information and thus could find promising applications in valleytronic devices. Current manipulation approaches for valley polarization of IXs are mainly limited in electrical field/doping, magnetic field or twist-angle engineering. Here, we demonstrate an electrochemical-doping method, which is efficient, in-situ and nonvolatile. We find the emission characteristics of IXs in WS2/WSe2 HSs exhibit a large excitonic/valley-polarized hysteresis upon cyclic-voltage sweeping, which is ascribed to the chemical-doping of O2/H2O redox couple trapped between WSe2 and substrate. Taking advantage of the large hysteresis, a nonvolatile valley-addressable memory is successfully demonstrated. The valley-polarized information can be non-volatilely switched by electrical gating with retention time exceeding 60 min. These findings open up an avenue for nonvolatile valley-addressable memory and could stimulate more investigations on valleytronic devices.

Tong Ye;Yongzhuo Li;Junze Li;Hongzhi Shen;Junwen Ren;Cun-Zheng Ning;Dehui Li

School of Optical and Electronic Information,Huazhong University of Science and Technology,430074 Wuhan,China;Department of Electronic Engineering,Tsinghua University,100084 Beijing,China;Frontier Science Center for Quantum Information,100084 Beijing,China;School of Electrical,Computer,and Energy Engineering,Arizona State University,Tempe,AZ 85287,USA;Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,430074 Wuhan,China

光：科学与应用（英文版）

[1]Tong Ye;Yongzhuo Li;Junze Li;Hongzhi Shen;Junwen Ren;Cun-Zheng Ning;Dehui Li-.Nonvolatile electrical switching of optical and valleytronic properties of interlayer excitons)[J].光：科学与应用（英文版）,2022(02):221-229

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