Resonantly Enhanced Hybrid Wannier-Mott-Frenkel Excitons in Organic-Inorganic Van Der Waals Heterostructures.

Hybrid excitons formed via resonant hybridization in 2D material heterostructures feature both large optical and electrical dipoles, providing a promising platform for many-body exciton physics and correlated electronic states. However, hybrid excitons at organic-inorganic interface combining the advantages of both Wannier-Mott and Frenkel excitons remain elusive. Here, hybrid excitons are reported in the copper phthalocyanine/molybdenum diselenide (CuPc/MoSe ₂ ) heterostructure (HS) featuring strong molecular orientation dependence by low-temperature photoluminescence and absorption spectroscopy. The hybrid Wannier-Mott-Frenkel excitons exhibit a large oscillator strength and display signatures of the Frenkel excitons in CuPc and the Wannier-Mott excitons in MoSe ₂ simultaneously through the delocalized electrons. The density functional theory (DFT) calculations further confirm the strong hybridization between the lowest unoccupied molecular orbital (LUMO) of CuPc and the conduction band minimum (CBM) of MoSe ₂ . The out-of-plane molecular orientation is further employed to tune the hybridization strength and tailor the hybrid exciton states. The results reveal the hybrid excitons at the CuPc/MoSe ₂ interface with tunability by molecular orientation, suggesting that the organic-inorganic HS constitutes a promising platform for many-body exciton physics such as exciton condensation and optoelectrical applications.
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