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Peer-reviewedCC BY 4.0Small (Weinheim an Der Bergstrasse, Germany)

Anomalous Sub‐Band Gap Emission at Room Temperature in Mixed‐Dimensional WS2/Cu2O Heterostructures

  • Osamah Kharsah1
  • Jonah von Kuczkowski1
  • Ahmed Shahin2
  • Rouaa Albalkhi1
  • Aya Al‐Amwi1
  • Ibrahim Titi1
  • Yossarian Liebsch1
  • Oliver Altenhoff1
  • Ulrich Hagemann3
  • Anke Hierzenberger1
  • Kevin Musselman2
  • Marika Schleberger1
  1. 1Faculty of Physics and CENIDE University of Duisburg‐Essen Duisburg Germany
  2. 2Mechanical Engineering University of Waterloo Waterloo Canada
  3. 3Interdisciplinary Center for the Analytics on the Nanoscale (ICAN) and CENIDE University of Duisburg‐Essen Duisburg Germany
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Abstract

Practical implementation of two‐dimensional (2D) transition‐metal dichalcogenides (TMDCs) in novel optoelectronics requires a fundamental understanding of carrier dynamics and interfacial states at 2D/3D heterostructures. Herein, a mixed‐dimensional p‐n junction based on monolayer tungsten disulfide (WS2) and cuprous oxide (Cu2O) is investigated. An anomalous emission (AE) at 1.66 eV is identified at room temperature, which is in the same spectral range as oxygen‐related Cu2O defect luminescence, but is enhanced at the heterointerface under 457 nm excitation. While this sub‐bandgap feature resembles the spectral signature of an interlayer exciton (ILX), its combined excitation‐wavelength, power, temperature, and bias dependence suggests that the emission is predominantly defect‐mediated and modified by the WS2/Cu2O interface. External modulation of the AE intensity is demonstrated via vertical bias, yielding an approximately 45% maximum‐to‐minimum modulation of the normalized AE/Cu2O PL area ratio over the applied bias range from −2 V to +2 V at 93 K. This modulation is asymmetric, showing a correlation between AE quenching and photocurrent generation under reverse bias. The spectral response peaks near the open‐circuit condition, marking a regime of efficient carrier accumulation and interfacial trapping. These findings identify WS2/Cu2O as a model hybrid interface for probing electrically tunable defect‐mediated recombination in mixed‐dimensional heterostructures.

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Cite

BibTeXRIS
BibTeX
@article{kharsah2026anomalous,
  title = {{Anomalous Sub‐Band Gap Emission at Room Temperature in Mixed‐Dimensional WS2/Cu2O Heterostructures}},
  author = {Osamah Kharsah and Jonah von Kuczkowski and Ahmed Shahin and Rouaa Albalkhi and Aya Al‐Amwi and Ibrahim Titi and Yossarian Liebsch and Oliver Altenhoff and Ulrich Hagemann and Anke Hierzenberger and Kevin Musselman and Marika Schleberger},
  journal = {Small (Weinheim an Der Bergstrasse, Germany)},
  year = {2026},
  month = sep,
  doi = {10.1002/smll.75662},
  url = {https://doi.org/10.1002/smll.75662},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Anomalous Sub‐Band Gap Emission at Room Temperature in Mixed‐Dimensional WS2/Cu2O Heterostructures
AU  - Osamah Kharsah
AU  - Jonah von Kuczkowski
AU  - Ahmed Shahin
AU  - Rouaa Albalkhi
AU  - Aya Al‐Amwi
AU  - Ibrahim Titi
AU  - Yossarian Liebsch
AU  - Oliver Altenhoff
AU  - Ulrich Hagemann
AU  - Anke Hierzenberger
AU  - Kevin Musselman
AU  - Marika Schleberger
PY  - 2026
DA  - 2026/09/21
JO  - Small (Weinheim an Der Bergstrasse, Germany)
DO  - 10.1002/smll.75662
UR  - https://doi.org/10.1002/smll.75662
AB  - Practical implementation of two‐dimensional (2D) transition‐metal dichalcogenides (TMDCs) in novel optoelectronics requires a fundamental understanding of carrier dynamics and interfacial states at 2D/3D heterostructures. Herein, a mixed‐dimensional p‐n junction based on monolayer tungsten disulfide (WS2) and cuprous oxide (Cu2O) is investigated. An anomalous emission (AE) at 1.66 eV is identified at room temperature, which is in the same spectral range as oxygen‐related Cu2O defect luminescence, but is enhanced at the heterointerface under 457 nm excitation. While this sub‐bandgap feature resembles the spectral signature of an interlayer exciton (ILX), its combined excitation‐wavelength, power, temperature, and bias dependence suggests that the emission is predominantly defect‐mediated and modified by the WS2/Cu2O interface. External modulation of the AE intensity is demonstrated via vertical bias, yielding an approximately 45% maximum‐to‐minimum modulation of the normalized AE/Cu2O PL area ratio over the applied bias range from −2 V to +2 V at 93 K. This modulation is asymmetric, showing a correlation between AE quenching and photocurrent generation under reverse bias. The spectral response peaks near the open‐circuit condition, marking a regime of efficient carrier accumulation and interfacial trapping. These findings identify WS2/Cu2O as a model hybrid interface for probing electrically tunable defect‐mediated recombination in mixed‐dimensional heterostructures.
SN  - 1613-6810
SN  - 1613-6829
ER  -