Fizika Nizkikh Temperatur: Volume 44, Number 11 (November 2018), p. 1532-1539 ( to contents , go back )
Influence of surface and polarization effects on electron energy transfer in colloidal solutions and films of ZnSe quantum dots
N.V. Bondar, M.S. Brodyn
Institute of Physics of the National Academy of Sciences 46 Nauki Ave., Kiev 03028, Ukraine
Institute for Scintillation Materials, STC “Institute for Single Crystals” of the National Academy of Sciences of Ukraine 60 Nauky Ave., Kharkov 61001, Ukraine
Received April 23, 2018, revised June 20, 2018, published online September 26, 2018
Optical absorption spectra of colloidal solutions and films based on ZnSe quantum dots (QD) stabilized with thioglycerol or thioglycolic acid and precipitated on spherical nanoparticles of silica dioxide are presented and studied. In addition to the usual quantum-size effect another two contributions to the QD excitons energy were revealed. The first is the surface contribution which appears in the colloidal solutions of stabilized with thioglycerol QD due to strong absorption of the thiol RSH group by the surface Zn and Se atoms. The second one (polarized) is additional, it arises in solid films of both type colloids due to the dielectric mismatch between QD materials and the surrounding matrix. It was shown for the first time that the energy transfer in the dense massif of ZnSe QDs on a spherical surface occurs due to the mechanism of strong interaction (hybridization of the orbitals) between neighbor QDs and that is described satisfactorily by a proposed theoretical model.
Key words: quantum dots, ZnSe, exciton, ligand, energy transfer.