Ultrahigh-Purity Single-Photon Emission from 2D WSe2 via Effective Suppression of Classical Emission

Wenjing Wu; Alex Strasser; Zhongqi Xiu; Kinfung Ngan; Thi D Hoang; Song Liu; Hangzheng Shen; Luke Nemetz Holtzman; James H Edgar; James C Hone; Vasili Perebeinos; Shuo Sun; Junichiro Kono; Xiaofeng Qian; Shengxi Huang

doi:10.1021/acs.nanolett.5c01718

Ultrahigh-Purity Single-Photon Emission from 2D WSe₂ via Effective Suppression of Classical Emission

Nano Lett. 2025 Jul 5. doi: 10.1021/acs.nanolett.5c01718. Online ahead of print.

Authors

Wenjing Wu^{1

2}, Alex Strasser³, Zhongqi Xiu¹, Kinfung Ngan⁴, Thi D Hoang⁴, Song Liu^{5

6}, Hangzheng Shen¹, Luke Nemetz Holtzman⁷, James H Edgar⁶, James C Hone⁵, Vasili Perebeinos⁸, Shuo Sun⁴, Junichiro Kono^{1

9

10

11

12}, Xiaofeng Qian^{3

13

14}, Shengxi Huang^{1

9

11

12}

Affiliations

¹ Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States.
² Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.
³ Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States.
⁴ JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0401, United States.
⁵ Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States.
⁶ Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, United States.
⁷ Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States.
⁸ Department of Electrical Engineering, University at Buffalo - The State University of New York, Buffalo, New York 14260-1660, United States.
⁹ Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.
¹⁰ Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States.
¹¹ Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States.
¹² Rice Advanced Materials Institute, Rice University, Houston, Texas 77005, United States.
¹³ Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, United States.
¹⁴ Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, United States.

PMID: 40616512
DOI: 10.1021/acs.nanolett.5c01718

Abstract

Single-photon emitters (SPEs) in two-dimensional WSe₂ offer high extraction efficiency and on-chip compatibility, but achieving high purity remains challenging. We present two strategies to suppress classical emission and enhance purity in WSe₂-based SPEs. In monolayer WSe₂, we exploited the presence and absence of valley-spin locking in free and bound excitons, respectively, to achieve purity of 98.3% via polarization control and 99.0% combined with near-resonant excitation. In bilayer WSe₂, we obtained 97.0% purity without polarization filtering, enabled by the indirect band gap and inversion symmetry. These values represent some of the highest as-measured purities reported for 2D TMD SPEs. Our methods do not require complex fabrication or instrumentation and are supported by first-principles calculations of the vacancy state of Se and spin degeneracy. This work offers practical pathways for realizing high-quality single-photon sources for emerging quantum technologies.

Keywords: 2D TMD; quantum emission; single-photon emission purity; valley polarization.