TY - DATA T1 - Electronic Structure and Luminescence of 1.1- and 1.4-nm Silicon Nanocrystals:  Oxide Shell versus Hydrogen Passivation PY - 2003/01/09 AU - Zhiyong Zhou AU - Louis Brus AU - Richard Friesner UR - https://acs.figshare.com/articles/journal_contribution/Electronic_Structure_and_Luminescence_of_1_1-_and_1_4-nm_Silicon_Nanocrystals_Oxide_Shell_versus_Hydrogen_Passivation/3733527 DO - 10.1021/nl025890q.s001 L4 - https://ndownloader.figshare.com/files/5825295 KW - Si nanocrystals KW - 2.4 eV KW - LUMO KW - band gap KW - Hydrogen Passivation KW - luminesce KW - Si 66 cores KW - DFT calculations KW - hydrogen passivation KW - Oxide passivation KW - Si 35 cores KW - 1.5 eV KW - Electronic Structure KW - transition KW - geometry optimization KW - HOMO N2 - The difference between oxide and hydrogen passivation of small Si nanocrystals is explored by all-electron, hybrid functional DFT calculations with unrestricted geometry optimization. Oxide passivation lowers the band gap by about 2.4 eV for Si35 cores and by about 1.5 eV for Si66 cores. The oxide-passivated nanocrystals have optically forbidden, indirect-gap-type transitions whereas the hydrogen-passivated nanocrystals have optically allowed, direct-gap-type transitions. The HOMO and LUMO are delocalized in both species. This result explains the experimental observation that hydrogen-passivated Si nanocrystals luminesce in the blue whereas oxide-passivated Si nanocrystals luminesce in the yellow-red. ER -