Thermionic Energy Conversion Based on Graphene van der Waals Heterostructures

Liang, Shi‐Jun; Liu, Bo; Hu, Wei; Zhou, Kun; Ang, L. K.

doi:10.1038/srep46211

Cited by 57 publications

(36 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2(b) and (d)]. This rather sizable discrepancy immediately reveals the incompatibility of Dirac cone approximation in the thermionic emission of high-energy electrons occurring at graphene/vacuum interface [10][11][12] or in the presence of photon absorption [2,13]. This fallacy of Dirac cone approximation arises from the fact that graphene band structure becomes highly nonlinear at high electron energy ε > 1 eV at which the Dirac cone approximation fails to capture this band nonlinearity.…”

Section: Resultsmentioning

confidence: 99%

Generalized High-Energy Thermionic Electron Injection at Graphene Interface

et al. 2019

Self Cite

View full text Add to dashboard Cite

Graphene thermionic electron emission across high-interface-barrier involves energetic electrons residing far away from the Dirac point where the Dirac cone approximation of the band structure breaks down. Here we construct a full-band model beyond the simple Dirac cone approximation for the thermionic injection of high-energy electrons in graphene. We show that the thermionic emission model based on the Dirac cone approximation is valid only in the graphene/semiconductor Schottky interface operating near room temperature, but breaks down in the cases involving highenergy electrons, such as graphene/vacuum interface or heterojunction in the presence of photon absorption, where the full-band model is required to account for the band structure nonlinearity at high electron energy. We identify a critical barrier height, Φ (c) B ≈ 3.5 eV, beyond which the Dirac cone approximation crosses over from underestimation to overestimation. In the high-temperature thermionic emission regime at graphene/vacuum interface, the Dirac cone approximation severely overestimates the electrical and heat current densities by more than 50% compared to the more accurate full-band model. The large discrepancies between the two models are demonstrated using a graphene-based thermionic cooler. These findings reveal the fallacy of Dirac cone approximation in the thermionic injection of high-energy electrons in graphene. The full-band model developed here can be readily generalized to other 2D materials, and shall provide an improved theoretical avenue for the accurate analysis, modeling and design of graphene-based thermionic energy devices.

show abstract

Section: Resultsmentioning

confidence: 99%

Generalized High-Energy Thermionic Electron Injection at Graphene Interface

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…A few years later, Mahan extended the work to multilayer thermionic refrigeration 26 [30][31][32][33][34][35][36][37][38][39] .…”

Section: Introductionmentioning

confidence: 99%

Thermionic enhanced heat transfer in electronic devices based on 3D Dirac materials

Huang

Lewis

Zhang

2019

Journal of Applied Physics

View full text Add to dashboard Cite

We calculate the heat transfer from electronic devices based on three-dimensional Dirac materials without and with thermionic cooling. Without thermionic cooling, the internal temperature of the devices is at best equal to and usually higher than the temperature of the surrounding environment. However, when thermionic cooling is employed to transport heat, the internal temperature can be considerably lower than the environmental temperature. In the proposed thermionic cooling process, the energy efficiency can be as high as 75% of the Carnot efficiency.

show abstract

“…In another work 11 a C th as low as 0.5 MW m −2 K −1 was experimentally estimated for a graphene-WSe 2 -graphene vdWH. A molecular dynamics study 12 evaluated a slightly higher C th of 17 MW m −2 K −1 for both graphene-WSe 2 -graphene and graphene-MoSe 2 -graphene vdWHs. The unprecedented low thermal conductance has renewed interests in solid-state thermionic energy conversion of vdWHs in recent years 10 , 12 – 14 .…”

Section: Introductionmentioning

confidence: 99%

“…Most of theoretical work on thermionic energy conversion uses the Richardson’s law for the thermionic current , where is the Richardson constant, e is the electron charge, m * is the electron effective mass, is the averaged electron transmission denoting the fraction of electrons transmitted from the metal to the semiconductor, k B is the Boltzmann constant, is the reduced Planck constant, T is the absolute temperature, and E b is the thermionic barrier height which is usually taken as a parameter to optimize the thermionic energy conversion efficiency 1 , 2 , 12 . A small E b of several k B T is found to be optimal for a single barrier thermionic energy converter 1 .…”

Section: Introductionmentioning

confidence: 99%

High-Performance Solid-State Thermionic Energy Conversion Based on 2D van der Waals Heterostructures: A First-Principles Study

Wang

Zebarjadi

Esfarjani

2018

Sci Rep

View full text Add to dashboard Cite

Two-dimensional (2D) van der Waals heterostructures (vdWHs) have shown multiple functionalities with great potential in electronics and photovoltaics. Here, we show their potential for solid-state thermionic energy conversion and demonstrate a designing strategy towards high-performance devices. We propose two promising thermionic devices, namely, the p-type Pt-G-WSe2-G-Pt and n-type Sc-WSe2-MoSe2-WSe2-Sc. We characterize the thermionic energy conversion performance of the latter using first-principles GW calculations combined with real space Green’s function (GF) formalism. The optimal barrier height and high thermal resistance lead to an excellent performance. The proposed device is found to have a room temperature equivalent figure of merit of 1.2 which increases to 3 above 600 K. A high performance with cooling efficiency over 30% of the Carnot efficiency above 450 K is achieved. Our designing and characterization method can be used to pursue other potential thermionic devices based on vdWHs.

show abstract

Thermionic Energy Conversion Based on Graphene van der Waals Heterostructures

Cited by 57 publications

References 54 publications

Generalized High-Energy Thermionic Electron Injection at Graphene Interface

Generalized High-Energy Thermionic Electron Injection at Graphene Interface

Thermionic enhanced heat transfer in electronic devices based on 3D Dirac materials

High-Performance Solid-State Thermionic Energy Conversion Based on 2D van der Waals Heterostructures: A First-Principles Study

Contact Info

Product

Resources

About