  Utilizing hot carriers is the crucial approach for solar cell to exceed the
thermodynamic detailed balance limit, yet effective extraction of hot carriers
in absorber materials via most commonly used semiconductor acceptors has been a
challenge in both materials and photophysics research for many years. Herein,
we build series of CsPbI3 quantum dot and fullerene derivative systems to
explore the decisive factors of this process and have for the first time
realized efficient hot carrier extraction in these systems (maximum extraction
efficiency ~ 84%). We find building the systems as state-coupled complexes
creates new carrier transport channels at about 0.22 eV above CsPbI3 quantum
dot bandgap, which facilitates highly efficient HC extraction. Our research
directly visualizes the inner connection of molecule interaction and ultrafast
hot carrier extraction. The knowledge and strategy gained here are of universal
meaning, taking an important step forward true hot carrier photovoltaics.
