High-Performance Self Powered Broadband Photodetection in Graphene-Contacted MoTe2 - WS2 van der Waals Heterostructures via Interfacial Band Engineering

Sep 30, 2026

Vertically stacked MoTe2/WS2 van der Waals heterostructures are used to fabricate a broadband, self-powered photodetector with few-layer graphene as transparent, tunable contact electrodes. Mechanical exfoliation and dry transfer maintain pristine interfaces. Optical, electrical, and DFT results show a type II band alignment that promotes efficient photocarrier separation, while graphene contacts enhance rectification beyond 10^5, suppress contact-induced recombination, and improve photocurrent. The device delivers broadband response over 220–850 nm with responsivity ~650 A W−1, detectivity ~1.3 × 10^12 Jones, and external quantum efficiency ~3.5 × 10^5%, supported by rapid, bias-dependent time-resolved behavior.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages16

Reading Time40 min

AccessFree to download

Introduction

2D TMDCs for optoelectronic devices

MoTe2 and WS2 complementarity for broadband detection

Graphene contact engineering in TMDC photodetectors

RESEARCH ARTICLE [www.small-journal.com](www.small-journal.com) High-Performance Self Powered Broadband Photodetection in Graphene-Contacted MoTe2 /WS2 van der Waals Heterostructures via Interfacial Band Engineering Muhammad Rabeel, Hammad Ghazanfar, Honggyun Kim, Ehsan Elahi, Syed Jazib Abbas Zaidi, Muneeb Ahmad, Faisal Ghafoor, Muhammad Wajid Zulﬁqar, Muhammad Suleman, Muhammad Abubakr, Muhammad Farooq Khan, and Deok-kee Kim* Van der Waals (vdW) heterostructures composed of 2D materials oﬀer a versatile platform for next-generation optoelectronic devices due to their tunable band structures, strong light matter interactions, and clean vdW interfaces. Here, this work reports on the fabrication and in depth characterization of a broadband photodetector based on a vertically stacked MoTe2/WS2 heterostructure with a few layer graphene serving as transparent, tunable contact electrodes. The device is assembled entirely through mechanical exfoliation and dry transfer, ensuring pristine interfaces and preserving the intrinsic properties of the materials. Systematic optical, electrical, and density functional theory (DFT) analysis reveal a type II band alignment at the MoTe2 WS2 interface, facilitating eﬃcient photocarrier separation. The incorporation of graphene contacts signiﬁcantly enhances rectiﬁcation behavior over 105 , suppresses contact induced recombination and improves photocurrent response due to their tunable work function and van der Waals bonding. The device exhibits a broadband photoresponse (220–850 nm), high responsivity (≈650 A W−1), large detectivity (≈1.3 × 1012 Jones), and external quantum eﬃciency (≈3.5 × 105 %). Time resolved studies demonstrate rapid, bias dependent photoresponse, making the device suitable for high speed photodetection. This study highlights the critical role of contact engineering and interfacial band alignment in optimizing 2Dheterostructure based optoelectronics. 1. Introduction 2D transition metal dichalcogenides (TMDCs) have emerged as key candidates for building ﬂexible, transparent, and atomically thin optoelectronic devices due to their tunable band gaps and strong light– matter interaction. [1,2] The ever growing demand for high performance photodetectors has prompted researchers to explore innovative materials and device architectures to meet the challenges of contemporary applications. [3,4] Heterostructures formed by stacking TMDCs enable unprecedented opportunities to engineer interfacial band alignment, facilitating charge separation and transport. [5–8] Among these materials, transition metal dichalcogenides (TMDCs) such as molybdenum ditelluride (MoTe2 ) and tungsten disulﬁde (WS2 ) have emerged as particularly attractive due to their tunable bandgapsand strong light–matter interactions. [9,10] MoTe2 , a p-type semiconductor with a narrow bandgap, oﬀers excellent absorption in the near infrared (NIR) region, M. Rabeel, H. Ghazanfar, M. Ahmad, F. Ghafoor, M. W. Zulﬁqar, M. F. Khan, D.-kee Kim Department of Electrical Engineering and Convergence Engineering for Intelligent Drone Sejong University Seoul 05006, South Korea E-mail: [deokkeekim@sejong.ac.kr](deokkeekim@sejong.ac.kr) The ORCID identiﬁcation number(s) for the author(s) of this article can be found under [https://doi.org/10.1002/smll.202508208](https://doi.org/10.1002/smll.202508208) © 2025 The Author(s) . Small published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modiﬁcations or adaptations are made. DOI: 10.1002/smll.202508208 M. Rabeel, H. Ghazanfar, H. Kim, M. Ahmad, F. Ghafoor, M. W. Zulﬁqar, D.-kee Kim Department of Semiconductor Systems Engineering Sejong University Seoul 05006, South Korea E. Elahi Department of Inorganic Chemistry University of Chemis

FAQs

What is the core device structure used for the photodetector?

The photodetector is a vertically stacked MoTe2/WS2 heterostructure with few-layer graphene serving as transparent, tunable contact electrodes.

How does interfacial band alignment affect photocarrier behavior?

A type II band alignment at the MoTe2/WS2 interface enables efficient spatial separation of photogenerated carriers across the junction.

What performance characteristics does the device achieve across the optical spectrum?

It shows broadband photoresponse from 220 to 850 nm, high responsivity (~650 A W−1), large detectivity (~1.3 × 10^12 Jones), and external quantum efficiency (~3.5 × 10^5%).

Sep 30, 2026

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