Fig. 2.

NIR-II photothermal effects of FePS@PPF. a Absorption spectra at different concentrations. b Normalized absorbance at 1064 nm or 600 nm is divided by the characteristic length of the cell (A/L). Normalized absorbance intensity per length of the cell (A/L) for λ = 1064 nm at various concentrations. c Photothermal rise curves as a function of concentrations under 1064 nm laser irradiation at 1.0 W/cm². d Photothermal heating curves at different power densities with the concentration 50 µg/mL. e Temperature changes during four laser on-off cycles. f Photothermal conversion efficiency. Redline: Photothermal effects with 1064 nm laser irradiation for 15 min and then the temperature change with laser off. Blueline: Time constant (τ) obtained from the cooling profile