Charge transport inside of organic crystals and lithium-containing metal oxides

2015 Fiscal Year Final Research Report

• Project/Area Number: 26800220
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Biological physics/Chemical physics/Soft matter physics
• Research Institution: Tohoku University
• Principal Investigator: Packwood Daniel 東北大学, 原子分子材料科学高等研究機構, 助教 (40640884)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: Organic semiconductors / Metal oxides / Lithium ion batteries / Bayesian networks

Outline of Final Research Achievements

[Part 1] Electrons in organic crystals become less mobile with temperature (A) and are highly localized (B). A stochastic model showed that charge transport in organic crystals depends upon correlated intermolecular vibrations. The weakening of this correlation with temperature explains (A). The localization of correlated vibrations explains (B). [Part 2] We analysed MD simulations of C60 crystals using Bayesian statistics and discovered a new mechanism for electronic coupling between C60 molecules. Here, the HOMO of one C60 molecule is modulated by its vibrations and the vibrations of a neighboring C60 molecule. The HOMO then excites more vibrations within the molecules, which then modulates the LUMO energy of the neighboring molecule. [3] We analysed Li+ ion diffusion in LiCoO2 by studying random walks on a hexagonal lattice. We found that an entropy barrier to Li+ diffusion which arises from simultaneous, localized Li+ motion in different parts of the crystal lattice.

Free Research Field

物理化学