Broadband optical absorption and photothermal properties of partially disordered MoSe2 nanospheres

The new broadband light-absorbing material is essential for effective utilization of solar energy. However, the size-controllable MoSe2 nanospheres for the applications in broadband light-absorbing and photothermal fields, as well as the role of partially disordered features on the optical responses have not been well investigated. Here, we prepare the partially disordered MoSe2 nanospheres by a facile solvothermal synthesis method and investigate the random impacts of the spherical diameter on optical responses. The MoSe2 nanospheres reveal dark black color and broadband absorption from ultraviolet to near-infrared wavelength without obvious absorption edge. The photothermal properties with super-continuous laser irradiation demonstrate that MoSe2 nanospheres have high photothermal conversion efficiency of about 44.8% in water and even also reach about 30.7% in ethanol. The superior light absorption could originate from free-carriers absorption, defective state absorption and resonant absorption. The results not only pave the way of two-dimensional material for disordered photonic researches, but also widen the potential applications of MoSe2 in saturable absorber and photothermal agent. [Display omitted] •Size-controllable MoSe2 nanospheres are prepared by a solvothermal synthesis method.•The randomness plays a key role in optical absorption and photothermal properties.•MoSe2 reveals high photothermal conversion efficiency of about 44.8% in water.•Photoabsorption comes from free-carrier, defective state and resonant absorption.