Reduction in thermal conductivity and tunable heat capacity of inorganic/organic hybrid superlattices

Ashutosh Giri*, Janne-Petteri Niemelä, Chester J. Szwejkowski, Maarit Karppinen, Patrick E. Hopkins

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

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    Abstract

    We study the influence of molecular monolayers on the thermal conductivities and heat capacities of hybrid inorganic/organic superlattice thin films fabricated via atomic/molecular layer deposition. We measure the cross plane thermal conductivities and volumetric heat capacities of TiO2- and ZnO-based superlattices with periodic inclusion of hydroquinone layers via time domain thermoreflectance. In comparison to their homogeneous counterparts, the thermal conductivities in these superlattice films are considerably reduced. We attribute this reduction in the thermal conductivity mainly due to incoherent phonon boundary scattering at the inorganic/organic interface. Increasing the inorganic/organic interface density reduces the thermal conductivity and heat capacity of these films. High-temperature annealing treatment of the superlattices results in a change in the orientation of the hydroquinone molecules to a 2D graphitic layer along with a change in the overall density of the hybrid superlattice. The thermal conductivity of the hybrid superlattice increases after annealing, which we attribute to an increase in crystallinity.

    Original languageEnglish
    Article number024201
    Number of pages7
    JournalPhysical Review B
    Volume93
    Issue number2
    DOIs
    Publication statusPublished - 11 Jan 2016
    MoE publication typeA1 Journal article-refereed

    Keywords

    • MOLECULAR LAYER DEPOSITION
    • ZINCONE THIN-FILMS
    • NANOCRYSTAL ARRAYS
    • TIO2 POLYMORPHS
    • TRANSPORT
    • TRANSPARENT

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