Optical Excitations in Cadmium Sulfide Nanoparticles

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• 作者：Johannes Frenzel ; Jan-Ole Joswig ; Gotthard Seifert
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：July 26, 2007
• 年：2007
• 卷：111
• 期：29
• 页码：10761 - 10770
• 全文大小：726K
• 年卷期：v.111,no.29(July 26, 2007)
• ISSN：1932-7455

文摘

Density functional-based calculations employing linear response theory have been performed on cadmiumsulfide nanoparticles with up to 2000 atoms. We have considered different stoichiometries, underlying crystalstructures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations(unsaturated, partly saturated, completely saturated). We find strong excitonic onset excitations. For the saturatedparticles, the quantum confinement effect in the lowest excitation is visible as the excitation energy decreasestoward the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introducetrapped surface states that lie below the lowest excitations of the completely saturated particles. Zincblende-and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles arerather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise toless pronounced spectra with lower oscillator strengths. Finally, we find a very good agreement of our datato experimentally available spectra and excitation energies.