Size effect on near infrared photothermal conversion properties of liquid-exfoliated MoS2 and MoSe2

Molybdenum disulfide and Molybdenum selenide (MoS2 and MoSe2) have been reported as the ptotothermal agent due to the excellent photothermal conversion property. The MoS2 and MoSe2 nanoflakes water dispersion solution were synthesized via the combination technology of grinding and sonication. The different size distribution of MoS2 has been selected by controlling centrifugation rate. MoS2 nanoflakes exhibit better photothermal ability than MoSe2 at the same concentration, while MoSe2 is easier to tune the temperature changing than the MoS2 by size selecting. The photothermal mechanism dependence of the lateral size and thickness is discussed based on the micro transport process. The carrier excess kinetic energy can be converted into a heat via phonon emission, which can result in more heat energy generated in the few-layer MoS2 nanoflakes than in multi-layer ones.