Ab-initio Study of the Electron Mobility in a Functionalized UiO-66 Metal Organic Framework

Abstract

This study leverages density function theory (DFT) accompanied with Boltzmann transport equation approaches to investigate the electronic mobility as a function of inorganic substitution and functionalization in a thermally stable UiO-66 metal organic framework (MOF). The MOFs investigated are based on Zr-UiO-66 MOF with three functionalization groups of benzene dicarboxylate (BDC), BDC functionalized with an amino group (BDC + NH${}_2$) and a nitro group (BDC + NO${}_2$). The design space of this study is bound by UiO-66(M)-R, [M=Zr, Ti, Hf; R=BDC, BDC+NO${}_2$, BDC+NH${}_2$]. The elastic modulus was not found to vary significantly over the structural modification of the design space for either functionalization and inorganic substitution. However, the electron-phonon scattering potential was found to be controllable by up to 30\% through controlled inorganic substitution in the metal clusters of the MOF structure. The highest electron mobility was predicted for a UiO-66(Hf${}_5$Zr${}_1$) achieving a value of approximately 1.4x10${}^{-3}$ cm${}^2$/V-s. It was determined that functionalization provides a controlled method of modulating the charge density, while inorganic substitution provides a controlled method of modulating the electronic mobility. Within the proposed design space the electrical conductivity was able to be increased by approximately three times the base conductivity through a combination of inorganic substitution and functionalization.

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• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Diffusion of Small Molecules in Metal Organic Framework Materials