Dipole-Aligned Energy Transfer between Excitons in Two-Dimensional Transition Metal Dichalcogenide and Organic Semiconductor

Efficient Förster resonant energy transfer is observed between excitons in a two-dimensional (2D) monolayer of the transition metal dichalcogenide, MoSe2, and an 2 nm thick layer of the organic material, 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA). The exciton transition dipoles are horizontally aligned, enabling efficient energy transfer between these dissimilar materials. Energy transfer is observed using time-resolved and steady state photoluminescence and photoluminescence excitation spectroscopy. Time-resolved measurements show a reduction in the donor (PTCDA) lifetime, and steady state emission experiments show a decrease in donor and an increase in acceptor (MoSe2) emission. Photoluminescence excitation spectra show a spectral dependence of the energy transfer process, with a maximum efficiency at the absorption maximum of the donor. The planar dipole orientation is determined using Fourier space imaging. The efficient energy transfer from low mobility organic materials to higher mobility 2D semiconductors along with their extremely large oscillator strengths presents an attractive platform for developing high efficiency energy harvesting systems that cover a wide spectral range.