| Popis: |
Colloidal quantum dots have been appearing as an remarkable substance for optoelec- tronic devices due to their tunable optical character emanating from quantum confinement. Electric conductivity through quantum dot film is always obstructed by the accompany of spacing ligands among them because of their insulating property. Application of nanosheets can significantly reduce these obstructions, while still keep the tunability of quantum confinement. It is anticipated that because of the better charge carrier mobility, an optoelectronic devices based on nanosheets will have improved performance. The present project describes the successfull synthesis of two-dimensional PbS nanosheets through oriented attachments of PbS nanocrystals. The reaction temperature was altered to tune the thickness of the nanosheets. Their bandgaps were measured by optical absorption and emission spectroscopy. The energy gap of the nanosheets depends on thickness as 1/L, exhibiting pure quasi-two-dimensional semiconductor systems with absolute one-dimensional confinement. This dependence is also confirmed by the ab-intio calculation using density functional theory. |
