Origins of thermal boundary conductance of interfaces involving organic semiconductors

Successful thermal management in nanostructured devices relies on control of interfacial thermal transport. Recent measurements have revealed poor thermal transport across interfaces between two dissimilar materials, e.g. organic semiconductors and metals. In such systems, the interfacial thermal conductance, G b , is dominated by the strength of interfacial bonding, but existing analytical models still fail to accurately predict G b , especially for organic-metal interfaces.Growing interest in this research area calls for comprehensive understandings of interfacial thermal transport across hybrid material interfaces. Here we demonstrate that spatial nonuniformity has to be assessed in the calculation of G b for interfaces with partial coverage or incommensurate growth that is characteristic of these interfaces. The interface between copper phthalocyanine (CuPc) and F.C.C metals (Ag, Al, Au) exhibits a six-fold difference between the metal's (~ 4 Å) and organic molecule's (~ 25 Å) lattice constant. Molecular dynamics simulations reveal the spatial variation of G b , and a model is developed that considers the spatial variations in phonon transmission, successfully predicting G b for many organic-metal interfaces.

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“…The calculations are in close agreement with MD simulations 28 . The values lie within error-bars of each data point.…”

Section: Thermal Boundary Conductance Modeling With Spatial Non-unsupporting

confidence: 78%

“…Additionally, it is believed that the interfacial bonding strength behaves like a low-pass filter 28,33,40 which weighs the frequency independent phonon transmission coefficient:…”

Section: Thermal Boundary Conductance Modeling With Spatial Non-unmentioning

confidence: 99%

Spatial nonuniformity in heat transport across hybrid material interfaces

et al. 2014

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“…For these applications, thermal issues are critical because the maximum light output is limited by overheating of the active region. Similar issues arise in emerging fields such as organic electronics, which rely on metal contacts to cool the thermally insulating polymer device regions (8). TBC also dominates the heat transfer between 1D, 2D, and layered nanomaterials and their substrates (9--11), configurations being proposed for future electronic devices (12,13).…”

Section: Motivation and Applicationsmentioning

confidence: 99%

Thermal Boundary Conductance: A Materials Science Perspective

Monachon

Weber

Dames

2016

Annu. Rev. Mater. Res.

198

140

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The thermal boundary conductance (TBC) of materials pairs in atomically intimate contact is reviewed as a practical guide for materials scientists. First, analytical and computational models of TBC are reviewed. Five measurement methods are then compared in terms of their sensitivity to TBC: the 3ω method, frequency-and time-domain thermoreflectance, the cut-bar method, and a composite effective thermal conductivity method. The heart of the review surveys 30 years of TBC measurements around room temperature, highlighting the materials science factors experimentally proven to influence TBC. These factors include the bulk dispersion relations, acoustic contrast, and interfacial chemistry and bonding. The measured TBCs are compared across a wide range of materials systems by using the maximum transmission limit, which with an attenuated transmission coefficient proves to be a good guideline for most clean, strongly bonded interfaces. Finally, opportunities for future research are discussed.

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“…Given the recent interest in thermal transport in organicbased nanocomposites [19][20][21][22][23] and heat transport across molecular interfaces [24][25][26][27][28][29][30], systematically studying the thermal conductivity of a series of ALD/MLD-grown hybrid SLs also provides an ideal platform to advance our understanding of phonon scattering at, and heat transfer across, thin molecular interfaces. These high-quality hybrid nanosystems also provide ideal materials to understand the heat transfer mechanisms in organic/inorganic SLs, and the interplay between phonon-boundary scattering and thermal boundary conductance across interfaces of identical materials separated by a well-defined molecular layer.…”

Section: Introductionmentioning

confidence: 99%

Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices

et al. 2016

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Nanomaterial interfaces and concomitant thermal resistances are generally considered as atomic-scale planes that scatter the fundamental energy carriers. Given that the nanoscale structural and chemical properties of solid interfaces can strongly influence this thermal boundary conductance, the ballistic and diffusive nature of phonon transport along with the corresponding phonon wavelengths can affect how energy is scattered and transmitted across an interfacial region between two materials. In hybrid composites composed of atomic layer building blocks of inorganic and organic constituents, the varying interaction between the phononic spectrum in the inorganic crystals and vibronic modes in the molecular films can provide a new avenue to manipulate the energy exchange between the fundamental vibrational energy carriers across interfaces. Here, we systematically study the heat transfer mechanisms in hybrid superlattices of atomic-and molecular-layer-grown zinc oxide and hydroquinone with varying thicknesses of the inorganic and organic layers in the superlattices. We demonstrate ballistic energy transfer of phonons in the zinc oxide that is limited by scattering at the zinc oxide/hydroquinone interface for superlattices with a single monolayer of hydroquinone separating the thicker inorganic layers. The concomitant thermal boundary conductance across the zinc oxide interfacial region approaches the maximal thermal boundary conductance of a zinc oxide phonon flux, indicative of the contribution of long wavelength vibrations across the aromatic molecular monolayers in transmitting energy across the interface. This transmission of energy across the molecular interface decreases considerably as the thickness of the organic layers are increased.

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Origins of thermal boundary conductance of interfaces involving organic semiconductors

Cited by 43 publications

References 34 publications

Spatial nonuniformity in heat transport across hybrid material interfaces

Spatial nonuniformity in heat transport across hybrid material interfaces

Thermal Boundary Conductance: A Materials Science Perspective

Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices

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