Impact of dark excitons on Förster-type resonant energy transfer between dye molecules and atomically thin semiconductors

Abstract

Interfaces of dye molecules and two-dimensional transition metal dichalcogenides (TMDCs) combine strong molecular dipole excitations with high carrier mobilities in semiconductors. Förster type energy transfer is one key mechanism for the coupling between both constituents. We report microscopic calculations of a spectrally resolved Förster induced transition rate from dye molecules to a TMDC layer. Our approach is based on microscopic Bloch equations which are solved selfconsistently together with Maxwells equations. This approach allows to incorporate the dielectric environment of a TMDC semiconductor, sandwiched between donor molecules and a substrate. Our analysis reveals transfer rates in the meV range for typical dye molecules in closely stacked structures, with a non-trivial dependence of the Förster rate on the molecular transition energy resulting from unique signatures of dark, momentum forbidden TMDC excitons.

Resonance Energy Transfer from Monolayer WS2 to Organic Dye Molecules: Conversion of Faint Visible‐Red into Bright Near‐Infrared Luminescence

“…The different dimensionality of the excitons in the two materials, namely delocalized Wannier-Mott excitons in the 2D plane of the TMDC and Frenkel excitons localized at the molecule (or delocalized in an aggregate comprising several molecules) is expected to result in peculiarities which are not captured by the classical Förster theory developed for molecular donor-acceptor systems as shown in theoretical works. [12,32] This calls for further in-depth experimental studies. Both Förster-and Dexter-transfer are short-ranged and this offers yet another application of RET.…”

“…This has motivated many studies on exciton transfer as well as charge transfer involving the ground and excited state in TMDCbased heterostructures. [2,3,4,[5][6][7][8] In particular, excited state charge transfer between the organic component and the TMDCs [5,9,10] as well as non-radiative resonance energy transfer (RET) from organic dye molecules to TMDCs [3,6,11,12] have been utilized to enhance the photosensitivity and to tune the spectral range in nanoscale photodetecting devices. [3,5,8,13] The reverse transfer of excitation energy, namely that from TMDCs to dye molecules is of special interest for the development of nanoscale electrically pumped light sources benefitting from the high PL quantum yield (up to 100%) of organic dyes as well as the wide tunability of their emission wavelength.…”

Dipolar Coupling at Interfaces of Ultrathin Semiconductors, Semimetals, Plasmonic Nanoparticles, and Molecules

“…The framework allows to derive diverse energy-transfer mechanisms between the different material systems on the same footing by considering the respective contributions in the Hamiltonian when deriving Heisenberg's equation of motion as illustrated in Sections 3-6. For each hybrid, the electric field is determined by Maxwell's equations, which can be accessed in the Green's function formalism [16,62]…”

“…[4][5][6][7][8][9][10][11][12][13] Moreover, the atomical thickness provides a strong sensitivity to the environment: atomically thin materials can be manipulated by the choice of the embedding material and its geometry [14] as well as by defects [15] or functionalization. [16] When coated in leaky cavities, 2D TMDCs exhibit an interesting interplay of phonon and photon dissipation, leading to anomalous dispersion and negative mass effects. [17] Due to the variety of feasible material combinations, functionalization proves to be a powerful tool for tailoring electronic and optical properties on the nanoscale.…”

Electronic Structure of Low‐Dimensional Inorganic/Organic Interfaces: Hybrid Density Functional Theory, G0W0, and Electrostatic Models

“…First-principles methods based on density functional theory (DFT) are the natural choice for these calculations, especially in the absence of experimental parameters that are necessary to set up model Hamiltonians. [4,5] The predictive power of DFT is, however, partially limited by the approximations taken for the electronic exchange and correlation (xc). Standard implementations based on the homogeneous electron gas model [6] are unreliable for inhomogeneous systems.…”