Entropy production in hot-phonon energy conversion to electric potential

Shin, SangJoon; Kaviany, Massoud

doi:10.1063/1.4819217

Cited by 7 publications

(6 citation statements)

References 19 publications

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“…Phonon recycling has a long history, which can be traced back to the discovery of the thermoelectric and thermionic effects. Modern exploration of phonon recycling mainly concentrates on the design of various new recycling architectures, including thermophotovoltaics 33 , photon-enhanced thermionics 34 , hot-phonon absorption barriers 35 and phonovoltaics 36 , 37 . Despite these efforts, very little experimental evidence has been found to support the concept of phonon recycling.…”

Section: Introductionmentioning

confidence: 99%

Acoustic phonon recycling for photocarrier generation in graphene-WS2 heterostructures

Wei

Sui

et al. 2020

Nat Commun

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Electron-phonon scattering is the key process limiting the efficiency of modern nanoelectronic and optoelectronic devices, in which most of the incident energy is converted to lattice heat and finally dissipates into the environment. Here, we report an acoustic phonon recycling process in graphene-WS 2 heterostructures, which couples the heat generated in graphene back into the carrier distribution in WS 2. This recycling process is experimentally recorded by spectrally resolved transient absorption microscopy under a wide range of pumping energies from 1.77 to 0.48 eV and is also theoretically described using an interfacial thermal transport model. The acoustic phonon recycling process has a relatively slow characteristic time (>100 ps), which is beneficial for carrier extraction and distinct from the commonly found ultrafast hot carrier transfer (~1 ps) in graphene-WS 2 heterostructures. The combination of phonon recycling and carrier transfer makes graphene-based heterostructures highly attractive for broadband high-efficiency electronic and optoelectronic applications.

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Section: Introductionmentioning

confidence: 99%

Acoustic phonon recycling for photocarrier generation in graphene-WS2 heterostructures

Wei

Sui

et al. 2020

Nat Commun

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“…Monte Carlo simulations predict much lower efficiency than the thermodynamic limit [17], and the efficiency drops rapidly with the applied field strength [16].…”

Section: Target B-atoms Transient Vibrationmentioning

confidence: 95%

“…Recent advances in computational quantum mechanics allowed for an extension of heat transfer research into thermoelectric materials and electron-phonon coupling. The function of quantum mechanics (ab initio treatments) is established as central to advances in heat transfer research [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Atomic-Level, Energy-Conversion Heat Transfer

Kaviany

2021

Journal of Heat Transfer

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Heat is stored in quanta of kinetic and potential energies in matter. The temperature represents the equilibrium and exciting occupation (boson) of these energy conditions. Temporal and spatial temperature variations and heat transfer are associated with the kinetics of these equilibrium excitations. During energy-conversion (between electron and phonon systems), the occupancies deviate from equilibria, while holding atomic-scale, inelastic spectral energy transfer kinetics. Heat transfer physics reaches nonequilibrium energy excitations and kinetics among the principal carriers, phonon, electron (and holes and ions), fluid particle, and photon. This allows atomic-level tailoring of energetic materials and energy-conversion processes and their efficiencies. For example, modern thermal-electric harvesters have transformed broad-spectrum, high-entropy heat into a narrow spectrum of low-entropy emissions to efficiently generate thermal electricity. Phonoelectricity, in contrast, intervenes before a low-entropy population of nonequilibrium optical phonons becomes a high-entropy heat. In particular, the suggested phonovoltaic cell generates phonoelectricity by employing the nonequilibrium, low-entropy, and elevated temperature optical-phonon produced population–for example, by relaxing electrons, excited by an electric field. A phonovoltaic material has an ultra-narrow electronic bandgap, such that the hot optical-phonon population can relax by producing electron-hole pairs (and power) instead of multiple acoustic phonons (and entropy). Examples of these quanta and spectral heat transfer are reviewed, contemplating a prospect for education and research in this field.

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“…Without an external phonon source, the first and second laws of thermodynamics require that the electric potential should decrease, converting to phonon energy and increasing the phonon entropy and population [6]. Since reduced phonon emission (or potential drop) is desired, less phonon entropy should be generated through the phonon recycling.…”

Section: Monte Carlo Simulations Phonon Recycling and Net Po-tementioning

confidence: 99%

“…1(a) to (d) [5,6] aimed at returning the emitted phonons to electric potential. The doping density is uniform and moderate (< 10 23 m −3 , assuming nondegenerated electrons), so the equilibrium electron density is also uniform and the ep interactions dominate.…”

Section: Introductionmentioning

confidence: 99%

Toward reversing Joule heating with a phonon-absorbing heterobarrier

Shin

Kaviany

2015

Phys. Rev. B

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Using graded heterobarrier placed along an electron channel, phonons emitted in joule heating are recycled in-situ by increasing the entropy of phonon-absorbing electrons. The asymmetric electric potential distribution created by alloy grading separates the phonon absorption and emission regions, and emission in the larger effective mass region causes momentum relaxation with smaller electron kinetic energy loss. These lead to smaller overall phonon emission and simultaneous potential-gain and self-cooling effects. Larger potential is gained with lower current and higher optical phonon temperature. The self-consistent Monte Carlo simulations complying with the lateral momentum conservation combined with the entropy analysis are applied to GaAs:Al electron channel with graded heterobarrier, and under ideal lateral thermal isolation from surroundings, the phonon recycling efficiency reaches 25% of the reversible limit at 350 K, and increases with temperature. The lateral momentum contributes to the transmission across the barrier, so partially non-conserving lateral momentum electron scattering (rough interface) can improve the efficiency.

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Entropy production in hot-phonon energy conversion to electric potential

Cited by 7 publications

References 19 publications

Acoustic phonon recycling for photocarrier generation in graphene-WS2 heterostructures

Acoustic phonon recycling for photocarrier generation in graphene-WS2 heterostructures

Atomic-Level, Energy-Conversion Heat Transfer

Toward reversing Joule heating with a phonon-absorbing heterobarrier

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