Within silicon nanocrystals experimental observations have found a trend of increased photoluminescence intensity as a function of decreasing temperature. To probe a hypothesis that nuclear motion, and the corresponding electronic structure, plays a significant role in the strength of radiative recombination ground state electronic structure and molecular dynamic calculations were performed within VASP. Silicon nanocrystals of various diameters, ranging from 1 to 2 nm were studied at multiple temperature regimes. The combinational effect of different simulation temperatures along with functional groups passivating the surface of the nanocrystals provide varying degrees of nuclear displacement along the molecular dynamic trajectories. Each Si atom within the nanocrystal has one of three coordinations depending on its location relative to the surface, where each coordination provides varying degrees of rigidity. From the dynamic calculations, one can obtain a time dependent photoluminescent spectra which exhibits the same effect observed experimentally. The time-dependent spectra also provides broadening of emission producing spectra with a non-zero linewidth, which is unattainable using standard DFT spectra methods.

Effects of thermal broadening and photoluminescence in functionalized silicon nanocrystals

253rd National Meeting (2017)

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