Search query: Self-powered photovoltaic photodetector established on lateral monolayer MoS2-WS2 heterostructures

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abstract: Abstract With the rapid development of modern semiconductor industry, power free or self powered devices become an indispensable part in the electronic components and optoelectronic products. Epitaxial connected TMDs lateral heterojunctions with the maximum built in potential at the hetero interface offer fast separation of the photo generated electron hole (e h) pairs without an external bias, which make them promising for self powered devices. However, so far, the photovoltaic performance of such structures are rarely studied. Here, we report the photovoltaic light sensors based on individual monolayer MoS2 WS2 in plane heterostructures that were created through a one step synthesis strategy. The in situ second harmonic generation (SHG) characterizations of this monolayer in plane heterostructures directly demonstrate their underlying symmetry and high orientation. The photovoltaic photodetectors designed on individual MoS2 WS2 in plane samples that operate in a self powered mode (zero bias) exhibits a spectral responsivity (Rl) of 4.36 mA/W and detectivity (D* of 4.36 x 1013 Jones under 28.64 mW/cm2 532 nm. The primary characteristics of the lateral heterostructure devices are attributed to the built in potential at the interface. The initial self powered light sensor in a monolayer heterostructures combined with the scalable growth can be further applied in other 2D heterostructures.
author_names: Wanhui Wu

Qi Zhang

Xing Zhou

Linfeng Li

Jianwei Su

Fakun Wang

Tianyou Zhai
title: Self powered photovoltaic photodetector established on lateral monolayer MoS2 WS2 heterostructures
year: 2018

abstract: Monolayer heterojunctions such as MoS2/WS2 are attractive for solar energy conversion applications because the interfacial electric field spatially separates charge carriers in less than 100 femtoseconds. Photoelectrochemical cells represent an intriguing platform to collect the spatially separated carriers. However, the recombination, transport, and interfacial charge transfer processes that take place following the ultrafast charge separation step have not been investigated. Here we demonstrate novel charge recombination and transport pathways in monolayer MoS2/WS2 photoelectrochemical cells by spatially resolving the net collection of carriers (i.e. the photocurrent) at the single nanosheet level. We discovered an excitation wavelength dependent recombination pathway that depends on the heterojunction stacking configuration and the carrier generation profile in the heterostructure. Photocurrent mapping measurements revealed that charge transport occurs parallel to the layers over micrometre scale distances even though the indium tin oxide electrode and liquid electrolyte provide efficient charge extraction pathways via intimate electron and hole selective contacts. Our results reveal how composition heterogeneity influences the performance of bulk heterojunction electrodes made from randomly oriented nanosheets and provide critical insight into the design of efficient heterojunction photoelectrodes for solar energy conversion applications.
author_names: Li Wang

M Tahir

Hongli Chen

Justin B Sambur
title: Probing charge carrier transport and recombination pathways in monolayer MoS2/WS2 heterojunction photoelectrodes.
venue: Nano letters
year: 2019

abstract: 2D monolayer molybdenum disulphide (MoS2) has been the focus of intense research due to its direct bandgap compared with the indirect bandgap of its bulk counterpart; however its photoluminescence (PL) intensity is limited due to its low absorption efficiency. Herein, we use gallium hemispherical nanoparticles (Ga NPs) deposited by thermal evaporation on top of chemical vapour deposited MoS2 monolayers in order to enhance its luminescence. The influence of the NP radius and the laser wavelength is reported in PL and Raman experiments. In addition, the physics behind the PL enhancement factor is investigated. The results indicate that the prominent enhancement is caused by the localized surface plasmon resonance of the Ga NPs induced by a charge transfer phenomenon. This work sheds light on the use of alternative metals, besides silver and gold, for the improvement of MoS2 luminescence.
author_names: Sergio Catalan-Gomez

Sourav Garg

Andres Redondo-Cubero

Nuria Gordillo

Alicia de Andres

Flavio Nucciarelli

Seonsing Kim

Patrick Kung

Jose Luis Pau
title: Photoluminescence enhancement of monolayer MoS2 using plasmonic gallium nanoparticles
year: 2019

abstract: Here we take a first step toward tackling the challenge of incomplete optical absorption in monolayers of transition metal dichalcogenides for conversion of photon energy, including solar, into other forms of energy. We present a monolayer MoS2 based photoelectrode architecture that exploits nanophotonic light management strategies to enhance absorption within the monolayer of MoS2, while simultaneously integrating an efficient charge carrier separation mechanism facilitated by a MoS2/NiOx heterojunction. Specifically, we demonstrate two extremely thin photoelectrode architectures for solar fuel generation: (i) a planar optical cavity architecture, MoS2/NiOx/Al, that improves optical impedance matching and (ii) an architecture employing plasmonic silver nanoparticles (Ag NPs) MoS2/Ag NPs/NiOx/Al, that further improves light absorption within the monolayer. We used a combination of numerical simulations, analytical models, and experimental optical characterizations to gain insights into the contributions
author_names: Shah Mohammad Bahauddin

Hossein Robatjazi

Isabell Thomann
title: Broadband Absorption Engineering to Enhance Light Absorption in Monolayer MoS2
year: 2016

abstract: Novel physical phenomena can emerge in low dimensional nanomaterials. Bulk MoS(2) a prototypical metal dichalcogenide, is an indirect bandgap semiconductor with negligible photoluminescence. When the MoS(2) crystal is thinned to monolayer, however, a strong photoluminescence emerges, indicating an indirect to direct bandgap transition in this d electron system. This observation shows that quantum confinement in layered d electron materials like MoS(2) provides new opportunities for engineering the electronic structure of matter at the nanoscale.
author_names: Andrea Splendiani

Liang Sun

Yuanbo Zhang

Tianshu Li

Jonghwan Kim

Chi Yung Chim

Giulia Galli

Feng Wang
title: Emerging photoluminescence in monolayer MoS2.
venue: Nano letters
year: 2010

abstract: Layer by layer stacking or lateral interfacing of atomic monolayers has opened up unprecedented opportunities to engineer two dimensional heteromaterials. Fabrication of such artificial heterostructures with atomically clean and sharp interfaces, however, is challenging. Here, we report a one step growth strategy for the creation of high quality vertically stacked as well as in plane interconnected heterostructures of WS2/MoS2 via control of the growth temperature. Vertically stacked bilayers with WS2 epitaxially grown on top of the MoS2 monolayer are formed with preferred stacking order at high temperature. A strong interlayer excitonic transition is observed due to the type II band alignment and to the clean interface of these bilayers. Vapour growth at low temperature, on the other hand, leads to lateral epitaxy of WS2 on MoS2 edges, creating seamless and atomically sharp in plane heterostructures that generate strong localized photoluminescence enhancement and intrinsic p n junctions. The fabrication of heterostructures from monolayers, using simple and scalable growth, paves the way for the creation of unprecedented two dimensional materials with exciting properties.
author_names: Yongji Gong

Junhao Lin

Xingli Wang

Gang Shi

Sidong Lei

Zhong Lin

Xiaolong Zou

Gonglan Ye

Robert Vajtai

Boris I Yakobson

Humberto Terrones

Mauricio Terrones

Bengkang Tay

Jun Lou

Sokrates T Pantelides

Zheng Liu

Wu Zhou

Pulickel M Ajayan
title: Vertical and in plane heterostructures from WS2/MoS2 monolayers.
venue: Nature materials
year: 2014

abstract: The growth and exfoliation of two dimensional (2D) materials have led to the creation of edges and novel interfacial states at the juncture between crystals with different composition or phases. These hybrid heterostructures (HSs) can be built as vertical van der Waals stacks, resulting in a 2D interface, or as stitched adjacent monolayer crystals, resulting in one dimensional (1D) interfaces. Although most attention has been focused on vertical HSs, increasing theoretical and experimental interest in 1D interfaces is evident. In plane interfacial states between different 2D materials inherit properties from both crystals, giving rise to robust states with unique 1D non parabolic dispersion and strong spin orbit effects. With such unique characteristics, these states provide an exciting platform for realizing 1D physics. Here, we review and discuss advances in 1D heterojunctions, with emphasis on theoretical approaches for describing those between semiconducting transition metal dichalcogenides MX 2 (with M Mo, W and X S, Se, Te) and how the interfacial states can be characterized and utilized. We also address how the interfaces depend on edge geometries (such as zigzag and armchair) or strain, as lattice parameters differ across the interface, and how these features affect excitonic/optical response. This review is intended to serve as a resource for promoting theoretical and experimental studies in this rapidly evolving field.
author_names: Oscar Avalos-Ovando

Diego Mastrogiuseppe

Sergio E Ulloa
title: Lateral heterostructures and one dimensional interfaces in 2D transition metal dichalcogenides.
venue: Journal of physics. Condensed matter an Institute of Physics journal
year: 2019

abstract: Atomically thin transition metal dichalcogenides (TMDC) have become a new platform for the development of next generation optoelectronic and light harvesting devices. Here, we report a Kelvin probe force microscopy (KPFM) investigation carried out on a type II photovoltaic heterojunction based on WSe2 monolayer flakes and a bilayer MoS2 film stacked in vertical configuration on a Si/SiO2 substrate. Band offset characterized by a significant interfacial dipole is pointed out at the WSe2/MoS2 vertical junction. The photocarrier generation process and phototransport are studied by applying a differential technique allowing to map directly two dimensional images of the surface photovoltage (SPV) over the vertical heterojunctions (vHJ) and in its immediate vicinity. Differential SPV reveals the impact of chemical defects on the photocarrier generation and that negative charges diffuse in the MoS2 a few hundreds of nanometers away from the vHJ. The analysis of the SPV data confirms unambiguously that light absorption results in the generation of free charge carriers that do not remain coulomb bound at the type II interface. A truly quantitative determination of the electron hole (e h) quasi Fermi levels splitting (i.e. the open circuit voltage) is achieved by measuring the differential vacuum level shift over the WSe2 flakes and the MoS2 layer. The dependence of the energy level splitting as a function of the optical power reveals that Shockley Read Hall processes significantly contribute to the interlayer recombination dynamics. Finally, a newly developed time resolved mode of the KPFM is applied to map the SPV decay time constants. The time resolved SPV images reveal the dynamics of delayed recombination processes originating from photocarriers trapping at the SiO2/TMDC interfaces.
author_names: Yann Almadori

Nedjma Bendiab

Benjamin Grevin
title: Multimodal Kelvin Probe Force Microscopy Investigations of a Photovoltaic WSe2/MoS2 Type II Interface.
venue: ACS applied materials interfaces
year: 2018

abstract: Recent developments in synthesis and nanofabrication technologies offer the tantalizing prospect of realizing various applications from twodimensional (2D) materials. A revolutionary development is to flexibly construct many different kinds of heterostructures with a diversity of 2D materials. These 2D heterostructures play an important role in semiconductor and condensed matter physics studies and are promising candidates for new device designs in the fields of integrated circuits and quantum sciences. Theoretical and experimental studies have focused on both vertical and lateral 2D heterostructures; the lateral heterostructures are considered to be easier for planner integration and exhibit unique electronic and photoelectronic properties. In this review, we give a summary of the properties of lateral heterostructures with homogeneous junction and heterogeneous junction, where the homogeneous junctions have the same host materials and the heterogeneous junctions are combined with different materials. Afterward, we discuss the applications and experimental synthesis of lateral 2D heterostructures. Moreover, a perspective on lateral 2D heterostructures is
title: Recent Advances in 2 D Lateral Heterostructures
year: 2019

abstract: Two dimensional (2 D) materials of atomic thickness have attracted considerable interest due to their excellent electrical, optoelectronic, mechanical, and thermal properties, which make them attractive for electronic devices, sensors, and energy systems. Scavenging the otherwise wasted energy from the ambient environment into electrical power holds promise to address the emerging energy needs, in particular for the portable and wearable devices. The versatile properties of 2 D materials together with their atomically thin body create diverse possibilities for the conversion of ambient energy. The present review focuses on the recent key advances in emerging energy harvesting devices based on monolayer 2 D materials through various mechanisms such as photovoltaic, thermoelectric, piezoelectric, triboelectric, and hydrovoltaic devices, as well as progress for harvesting the osmotic pressure and Wi Fi wireless energy. The representative achievements regarding the monolayer heterostructures and hybrid devices are also discussed. Finally, we provide a discussion of the challenges and opportunities for 2 D monolayer material based energy harvesting devices in the development of self powered electronics and wearable technologies.
author_names: Fengru Fan

Wenzhuo Wu
title: Emerging Devices Based on Two Dimensional Monolayer Materials for Energy Harvesting
venue: Research
year: 2019