Directed Hot-Electron Transport in Quasi-One-Dimensional Antimony Selenide.

Extracting hot carriers prior to thermalization is a long-standing challenge for surpassing the Shockley-Queisser limit in photovoltaic and optoelectronic devices. Antimony selenide (Sb₂Se₃), featuring quasi-one-dimensional ribbon-like crystal motifs, has recently emerged as a promising platform for hot-carrier utilization. However, directly resolving the associated ultrafast extraction current remains elusive. Here, by employing polarization-phase-resolved THz emission spectroscopy, we visualized the directed transient hot-electron extraction current at the Sb₂Se₃/SnO₂ interface and identify an ∼1.2 eV pump photon energy threshold by a Fowler-type photoemission model, consistent with the direct band gap of the Sb₂Se₃. These results position THz emission spectroscopy as a powerful, noncontact metrology for mapping ultrafast and anisotropic hot-carrier dynamics and provide design principles for directional hot-carrier management in Sb₂Se₃-based energy-conversion devices.