The photoluminescence (PL) spectra from colloidal solution of coated semiconductor CdS/PbS nanoparticles, which are synthesized by a cation-exchanging colloidal method, are measured at room temperature. The PL spectra from S vacancies (Vs) and Cd-S composite vacancies (VCd-S) in CdS and CdS/PbS nanoparticles have been investigated. The PL of Vs can be quenched only by the Pb caption modified in the surface of CdS. The PL of VCd-S in CdS nanoparticles appears in about 1100 nm. The PL of VCd-S in CdS/PbS nanoparticles shifts to longer wavelengths as the quantity of PbS increases. The shift and intensity variation of the PL peak from VCd-S in CdS/PbS can be explained by a quantum confinement model of coated nanoparticles; the excited energy gap (HOMO-LUMO) is not only dependent on the size of the particles but also strongly dependent on the core/shell ratio of the coated nanoparticles. The PL energy gap (LUMO-VCd-S) is also strongly dependent on the core/shell ratio.
ASJC Scopus subject areas
- 化学 (全般)