| Autor: |
Tran TX; Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.; Center for Ultrafast Phase Transformation, Department of Physics, Sogang University, Seoul 04107, Republic of Korea., Jang YJ; Solar Energy Research Institute of Singapore (SERIS), National University of Singapore (NUS), Singapore 117574., Vu VT; Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea., Jung CW; Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea., Do VD; Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea., Jin Y; Department of Physics, Pusan National University, Busan 46241, Republic of Korea., Lee J; Department of Physics, Pusan National University, Busan 46241, Republic of Korea., Kim H; Center for Ultrafast Phase Transformation, Department of Physics, Sogang University, Seoul 04107, Republic of Korea., Kim JH; Department of Physics, Pusan National University, Busan 46241, Republic of Korea. |
| Abstrakt: |
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 x , 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. |
