Resonant electronic excitation energy transfer by Dexter mechanism in the quantum dot system

Abstract

Abstract. In present work the energy transfer between quantum dots by the exchange (Dexter) mechanism is analysed. The interdot Coulomb interaction is taken into consideration. It is assumed that the quantum dot-donor and the quantum dot-acceptor are made from the same compound A3B5 and embedded in the matrix of other material creating potential barriers for electron and holes. The dependences of the energy transfer rate on the quantum-dot system parameters are found using the Kane model that provides the most adequate description spectra of semiconductors A3B5. Numerical calculations show that the rate of the energy transfer by Dexter mechanism is comparable to the rate of the energy transfer by electrostatic mechanism at the distances approaching to the contact ones. IntroductionMethods based on nonradiative energy transfer between quantum dots are in considerable current use in biology and medicine. The strong dependence of the energy transfer rate on the distance between the energy donor and the energy acceptor enables to detect the formation of antigenantibody complexes, ensyme-substrate complexes, the DNA hybridization and cleavage [1] and also to study the structure and dynamics of biomolecules, where measurements of small distance within the molecule are necessary [2][3][4]. Results of these investigations are of the great importance for diagnostics and therapy of diseases, among which are oncological ones [5], (see also the literature in [1]). A correct interpretation of experimental data requires the adequate theory development. Resonant electronic excitation energy transfer occurs due to electricdipole-dipole, electric-dipole-quadrupole and higher multipole interactions and the exchange interactions between the energy donor and the energy acceptor. The first interactions are of an electrostatic nature, the last one has its origin in the antisymmetry of the electronic wave function of the system including an energy donor and an energy acceptor. An equality of electron excitation energies in donor and acceptor is a necessary condition for the resonant energy transfer which follows from the energy conservation law. The theory descriptive of the energy transfer between molecules due dipole-dipole interaction has been developed by Forster [6]. Subsequently, Dexter developed the theory to describe the electrostatic and exchange mechanisms of the energy transfer between impurity atoms or ions in an insulating crystal [7]. It was indicated that the exchange contribution in the energy transfer can be important in two situations: first, distance between donor and acceptor is short and the donor and acceptor wave functions are not strong

Constructing Concentration and Temperature Controllable Blue-Green Emission in a Single-Component Solid-State Phosphor

“…In order to understand the exchange procedure and the relationship between the defect luminescence center and the Tb 3+ luminescence center, the excitation energy transfer (EET) ,− theory by Förster and Dexter was employed. In the case of Y 2– x Tb x CaGe 4 O 12 , assuming that the chromophores involved are singlet states and no multiexciton states are considered, the blue and the green two parts both have their two distinctive chromophores, the donor and the acceptor.…”

Surface-Mediated Energy Transfer and Subsequent Photocatalytic Behavior in Silicon Carbide Colloid Solutions

“…Indeed, the particle–particle interaction can explain the measured ET in a colloid solution and its concentration dependency. Both resonant ET , and Dexter electron transfer , are well-known for semiconductor quantum dots. Quantum confinement results in the enlargement of the gap between occupied and empty energy levels when the size of a semiconductor particle is reduced below the exciton Bohr radius.…”

Valley-selective energy transfer between quantum dots in atomically thin semiconductors

“…2 b), where and nl and mk ) are the valley index and two quantum numbers of the exciton in the donor (acceptor). Here we consider the range of distances between the donor and acceptor, , much smaller that the de Broglie wavelength of the annihilated exciton and neglect effects of exchange and radiation transfer 47 , 48 , but take into the account the multipole nature of the Coulomb interaction 36 . With these assumptions, the energy transfer depends on the matrix elements of the Coulomb potential where and are the 2D center-of-mass vectors originating at the centers of the donor and acceptor.…”

“…Then, energy transfer is related to the annihilation of an exciton F (α) 1,nl in the donor and the creation of an , where α and nl (β and mk) are the valley index and two quantum numbers of the exciton in the donor (acceptor). Here we consider the range of distances between the donor and acceptor, s = (d 2 + h 2 ) 1/2 , much smaller that the de Broglie wavelength of the annihilated exciton and neglect effects of exchange and radiation transfer 47,48 , but take into the account the multipole nature of the Coulomb interaction 36 . With these assumptions, the energy transfer depends on the matrix elements of the Coulomb potential…”