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Updated: Jun 14, 2025

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Augmented Extraction Efficiency of a Hot D Exciton in MoS2 via Intervalley Scattering
Thanh-Xuan Tran1,2, Yu Jin Jang3, Van-Tu Vu4
1Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Abstract:
Prolonging hot carrier cooling, a crucial factor in optoelectronic applications, including hot carrier photovoltaics, presents a significant challenge. High-energy band-nesting excitons within parallel bands offer a promising and underexplored avenue for addressing this issue. Here, we exploit an exceptional D exciton cooling prolongation of 2 to 3 orders of magnitude compared to sub-picosecond in typical transition metal dichalcogenides (TMDs) owing to the complex Coulomb environment and the sequential and mismatch-valley relaxation. Simultaneously, the intervalley scattering upconversion of band-edge excitons with the slow D exciton formation in the metastable Γ valley/hill also reduces the cooling rate. We successfully extract D and C excitons as hot carriers through integrating with various thicknesses of TiO, achieving the highest efficiency of 98% and 85% at a Ti thickness of 2 nm. Our findings highlight the potential of band-nesting excitons for extending hot carrier cooling time, paving the way for advancements in hot carrier-based optoelectronic devices.
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