Influence of interfacial oxide on the optical properties of single layer CdTe/CdS quantum dots in porous silicon scaffolds

摘要

Using a combination of continuous wave and time-resolved spectroscopy, we study the effects of interfacial conditions on the radiative lifetimes and photoluminescence intensities of sub-monolayer colloidal CdTe/CdS quantum dots (QDs) embedded in a three-dimensional porous silicon (PSi) scaffold. The PSi matrix was thermally oxidized under different conditions to change the interfacial oxide thickness. QDs embedded in a PSi matrix with ～0.4 nm of interfacial oxide exhibited reduced photoluminescence intensity and nearly five times shorter radiative lifetimes (～16 ns) compared to QDs immobilized within completely oxidized, porous silica (PSiO_2) frameworks (～78 ns). The exponential dependence of QD lifetime on interfacial oxide thickness in the PSi scaffolds suggests charge transfer plays an important role in the exciton dynamics.