Energy Transport of Hybrid Charge-Transfer Excitons.

Abstract

We investigate the energy transport in an organic-inorganic hybrid platform formed between semiconductors that support stable room-temperature excitons. We find that following photoexcitation, fast-moving hot hybrid charge-transfer excitons (HCTEs) are formed in about 36 ps via scattering with optical phonons at the interface between j-aggregates of organic dye and inorganic monolayer MoS2. Once the energy falls below the optical phonon energy, the excess kinetic energy is relaxed slowly via acoustic phonon scattering, resulting in energy transport that is dominated by fast-moving hot HCTEs that transition into cold HCTEs in about 110 ps. We model the exciton-phonon interactions using Fröhlich and deformation potential theory and attribute the prolonged transport of hot HCTEs to phonon bottleneck. We find that the measured diffusivity of HCTEs in both hot and cold regions of transport was higher than the diffusivity of MoS2 A exciton and verify these results by conducting the experiments with different excitation energies. This work not only provides significant insight into the initial energy transport of HCTEs at organic-inorganic hybrid interfaces but also contributes to the formulation of a complete physical picture of the energy dynamics in hybrid materials, which are poised to advance applications in energy conversion and optoelectronic devices.