Colloidal semiconductor quantum dots with tunable surface composition.

Wei, Helen Hsiu-Ying; Evans, Christopher M; Swartz, Brett D; Neukirch, Amanda J; Young, Jeremy; Prezhdo, Oleg V; Krauss, Todd D · Nano Lett · 2012

basic_science · Level V

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Abstract

Colloidal CdS quantum dots (QDs) were synthesized with tunable surface composition. Surface stoichiometry was controlled by applying reactive secondary phosphine sulfide precursors in a layer-by-layer approach. The surface composition was observed to greatly affect photoluminescence properties. Band edge emission was quenched in sulfur terminated CdS QDs and fully recovered when QDs were cadmium terminated. Calculations suggest that electronic states inside the band gap arising from surface sulfur atoms could trap charges, thus inhibiting radiative recombination and facilitating nonradiative relaxation.

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