Size effect features and mechanism of luminescence of colloidal PbS quantum dots, passivated with thioglicolic acid

This paper presents new regularities of the size effect in IR luminescence of semiconductor colloidal PbS quantum dots, passivated with thioglycolic acid molecules (PbS/TGA QDs). It was found that decrease in the average PbS/TGA QDs size of the sample from 4.9 nm to 2.6 nm produces the luminescence peak shifts from 1350 nm to 865 nm. At that time, in the excitation spectrum the peak due to exciton absorption shifts from 1235 nm to 707 nm. The Stokes shift increases from 0.086 to 0.32 eV. The study of time-resolved luminescence showed that the luminescence decay is complex non-exponential it, that is determined by the statistical distribution of luminescence quenchers in PbS/TGA QDs over the ensemble. The complex of the obtained experimental results made it possible to conclude that the observed luminescence is determined by the radiative annihilation of exciton in PbS/TGA QDs.