Using this setup, the solutions were irradiated with the 470 nm laser for 400 s with an irradiance of 0.68 W.cm -2 . After extinction of the laser, a return to natural room temperature comes after 800 s. The temperature of the solution is recorded with a digital thermometer with an accuracy of 0.1°C every 0.5 s. The photothermal conversion efficiency was calculated following the method reported by Roper. The resistance to photothermal fatigue is studied by performing 5 cycles as described above (irradiation then return to room temperature) with an absorption measurement between each cycle.