Fig. 3. (A) Photothermal heating curves of water, TPP NPs, 1-Ir NPs and 4-Ir NPs (6 × 10⁻⁵ M) in aqueous solution under irradiation (635 nm, 0.8 W cm⁻²); (B) 4-Ir NPs with different concentrations under irradiation (635 nm, 0.8 W cm⁻²); (C) 4-Ir NPs (6 × 10⁻⁵ M) with different laser power densities; (D) photothermal effect of the 4-Ir NPs (6 × 10⁻⁵ M) dispersions under irradiation (635 nm, 0.8 W cm⁻²), which was turned off after irradiation for 300 s; (E) plot of cooling time versus negative natural logarithm of the temperature obtained from the cooling stage of the 4-Ir NPs; (F) temperature variations of the 4-Ir NPs under irradiation (635 nm, 0.8 W cm⁻²) for five light on/off cycles (300 s of irradiation for each cycle).