ИСТИНА

Colloidal CdSe quantum dots (QDs) are in the lead position among other due to their optical properties. However, the bulk band gap of CdSe (1,74 eV) doesn’t allow effective emission of undoped QDs in the IR-range. Our approach is to obtain highly-defective CdSe QDs, which have an intensive near-IR photoluminescence (PL) (ranging up to 0,9 eV) and high quantum yield (QY) (that exceeds the QY of undoped by more than two times). In our work we used colloidal method and silver halides (AgHal) were added during nanoparticles’ growth. It was found that a little amount of AgHal leads to the tetrapods’ formation. And the further increase of AgHal amount in synthesis has led to the tetrapods’ destruction and the formation of large ellipsoidal nanoparticles (EPs). A threshold concentration of AgHal above which tetrapods fully disappear has been established. Nowadays, it is known that halide-ions cause anisotropy of QDs, while silver-doped CdSe nanoparticles are unstable. An overlap between the two conditions allowed to obtain EPs, that have formed from tetrapods at high temperatures. EPs’ PL has two bands – exciton (with maximum ~1,8 eV) and a wide band in low-energy region (with maximum ~1,4 eV). The second band is associated with structure defects and has a long PL lifetime (9 s at 1,3 eV), which could be useful for crating population inversion on this electron level.