Upon irradiation, the temperature initially increases to reach a maximum of DT=30°C then decreases after 300s irradiation time (Figure ). The photothermal conversion efficiency (η) was determined from equation 12 (see experimental part). Table shows similar values of η for all 6a-c compounds of about 28%, while the efficiency of 6d, which bears a stronger dimethylamine donor group, almost doubled reaching 50%. The latest is also definitely more efficient than DCM, whose η was estimated to 28%. To further evaluate the potential of those molecules as PTT agents, the resistance to photothermal fatigue was determined. To do so, 20 µM solutions in DMSO have been irradiated