In our previous studies we explored structures and spectra of SiC clusters and polymers that may have potential for photovoltaics and excitonics applications. We find that the thermodynamically stable closo-Si12C12 cluster is a charge-transfer moiety having capability to assemble 1D polymer chains, 2D polymer layers and 3D crystals. Reactive unsaturated dangling bonds on corner and side Si atoms in a closo-Si12C12 cluster can be passivated by bonding hydrogen atoms. The unsaturated valances on corner and side Si atoms are also expected to bond to hydroxyl groups. Dehydration reactions between the hydroxyl groups on adjacent hydroxylated closo-Si12C12 clusters can form oligomers or polymers connected through siloxane links instead of Si-Si bonds. In this work, we first studied the structures and stabilities of hydroxylated closo-Si12C12 molecules having different numbers of -OH groups bonded at different silicon sites. We then explore products of dehydration reactions between stable hydroxylated closo-Si12C12 molecules to form closo-Si12C12 siloxane oligomers or polymers. And finally we evaluate the polymeric structures for their energetic and optical properties. We employed B3LYP and PBE0 functionals with cc-pVTZ basis sets to perform DFT and TDDFT calculations respectively to optimize geometries and to compute excitation energies and photo-absorption spectra in this work.

Closo-Si12C12 Molecule from cluster to crystal: Structure and properties of closo-Si12C12 siloxane polymers

253rd National Meeting (2017)

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