First-Principles Study on Grafting of Diazonium Salts to Silicon Surfaces
Yulun Han and Dmitri S. Kilin
Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102
Aryl diazonium salts are one of the most popular surface modifiers due to their handiness, scalability, and low cost. In this work, we investigate the chemical reaction of benzenediazonium bromide with hydrogenated crystalline (111) silicon slab using density functional theory (DFT) based ab initio molecular dynamics (AIMD). The AIMD calculations are performed at high temperatures to facilitate the chemical reactions. In the AIMD trajectory, one observes a sequence of reaction steps including the loss of N2 from the diazonium cation and proton transfer from the surface to the bromide that eliminates HBr. In addition, we calculate the optoelectronic properties of hydrogenated crystalline (111) silicon slabs with and without attaching a phenyl ring onto the sp3Si atom on the surface. The computation of photoluminescence spectra relies on the sampling over adiabatic molecular dynamics trajectories by taking into account fluctuations of frontier orbitals’ energies associated with thermal motion of nuclei.1-3 The adiabatic molecular dynamics also serves as a foundation for the calculation of the nonradiative relaxation of charge carriers by a reduced density matrix formalism with Redfield theory.4-6
References
1. Vogel, D. J.; Kilin, D. S., First-Principles Treatment of Photoluminescence in Semiconductors. J. Phys. Chem. C 2015, 119, 27954-27964.
2. Brown, S. L.; Vogel, D. J.; Miller, J. B.; Inerbaev, T. M.; Anthony, R. J.; Kortshagen, U. R.; Kilin, D. S.; Hobbie, E. K., Enhancing Silicon Nanocrystal Photoluminescence through Temperature and Microstructure. J. Phys. Chem. C 2016, 120, 18909-18916.
3. Han, Y.; Anderson, K.; Hobbie, E. K.; Boudjouk, P.; Kilin, D. S., Unraveling Photodimerization of Cyclohexasilane from Molecular Dynamics Studies. J. Phys. Chem. Lett. 2018, 9, 4349-4354.
4. Han, Y.; Tretiak, S.; Kilin, D., Dynamics of Charge Transfer at Au/Si Metal-Semiconductor NanoInterface. Mol. Phys. 2014, 112, 474-484.
5. Han, Y.; Micha, D. A.; Kilin, D. S., Ab Initio Study of the Photocurrent at the Au/Si Metal– Semiconductor Nanointerface. Mol. Phys. 2015, 113, 327-335.
6. Han, Y.; Meng, Q.; Rasulev, B.; May, P. S.; Berry, M. T.; Kilin, D. S., Photoinduced Charge Transfer Versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes. J. Chem. Theory Comput. 2017, 13, 4281-4296.