Crystalline phases-mediated discriminative photothermal properties in plasmonic copper-based sulfides

Understanding the corelation between crystalline phases of semiconducting nanomaterials and their photophysical properties is of great significance for developing hihgly eficient photothermal agents. Herein we comparatively investigated the crystalline phases-mediated discriminative photothermal effects in copper-based sulfides and their ultrafast carrier dynamics. The unique S-S double bond and semimetallic band gap of CuS enable a strong localized surface plasmon resonance (LSPR) effect, showing intense near-infrared absorption and much higher photothermal conversion efficiency (PCE) than those of copper-deficient Cu_1.81S and Cu₇S₄. The mechanism study demonstrates that the semimetallic CuS exhibited strong carrier-phonon coupling (4.255 × 10¹⁷ J·K⁻¹·s⁻¹·m⁻³) and rapid lattice heating within 190 femtoseconds during the non-radiative relaxation process, such efficient photothermal conversion has negligible energy losses such as the hot electron radiation. Our results evidence that CuS poseesses superior PCE among copper-based sulfide nanomaterials due to the unique crystalline phases-mediated discriminative photothermal effects. This study helps to deepen our understanding of the crystal structure-carrier dynamics-photothermal function relationships in copper-based sulfides, providing new insight into the rational development of high PCE nanomaterials with imaproved performace for practical applications.