Förster energy transfer from a semiconductor quantum well to an organic material overlayer

Abstract

We predict an efficient electronic energy transfer from an excited semiconductor quantum well to optically active organic molecules of the nearby medium (substrate and/or overlayer). The energy transfer mechanism is of the Forster type and, at semiconductor-organic distances of about 50 A, can easily be as fast as 10-100 ps, which is about an order of magnitude shorter than the effective exciton lifetime in an isolated quantum well. In such conditions, the Wannier-Mott exciton luminescence is quenched and the organic luminescence is efficiently turned on. We consider both free as well as localized quantum well excitons discussing the dependence of the energy transfer rate on temperature and localization length. A similar mechanism for the non-radiative energy transfer to the organic overlayer molecules from unbound electron-hole pairs excited in the 2D continuum is shown to be much less competitive with respect to other relaxation channels inside the inorganic quantum well (in particular, 2D exciton formation).