| Metamaterial absorbers based on surface plasmon resonance can achieve perfect absorption of light over a wide bandwidth with excellent tunability,which has sparked widespread research interest.These absorbers are accompanied by significant photothermal conversion during efficient light absorption,and studying their mechanisms can provide new ideas and approaches for efficient photothermal conversion,providing theoretical and experimental foundations for developing new efficient photothermal conversion devices.In this paper,two metamaterial broadband perfect absorbers that can efficiently obtain photothermal energy are proposed and verified through modeling,design,and simulation calculations,and their application prospects are explored.The main research contents are as follows:1.We propose a refractory metal hollow cavity metasurface,which is composed of stacked Cr and Si O2 thin films.With the combined effect of local surface plasmon resonance,cavity resonance,and refractory material intrinsic response,perfect absorption of the ultra-wide band of 310-4235 nm is achieved,with an absorption efficiency of over 97%under AM1.5G illumination.More importantly,this refractory metasurface has efficient photothermal generation and extremely sensitive thermal reaction ability,and with the use of concentrators,it is easy to obtain considerable steady-state temperatures in both water and air.It can be excited using light of different wavelengths to obtain almost the same photothermal response.The inherent absorption loss and natural thermal stability of refractory metals over a wide frequency range ensure broadband efficient absorption and corresponding thermal response.Cavity metasfaces enable further improvements in spatial light field capture and open the way for direct interaction photothermal manipulation.These excellent properties make it promising for a wide range of applications in solar energy,photothermal therapy and radiation measurement,and energy steam generation.2.We have designed a metamaterial broadband absorber based on refractory metal Ti N and Si O2,which can perform photothermal conversion efficiently to meet the needs of various photothermal applications.The absorption bandwidth of the absorber covers the ultra-wide band from ultraviolet to near infrared,with an average absorption rate up to 96.7%,and the average absorption rate of 770 nm-955 nm and 1310 nm-1630 nm exceeds 99%.The absorption spectrum of the absorbent almost coincides with the standard spectrum of the Earth’s surface radiation,and the weighted absorption efficiency of the radiation energy is more than 95.6%.Under the action of local surface plasmon,efficient photoheat is generated in the absortor structure.Under the natural light incident,the equilibrium temperature with the surrounding environment reaches48.2℃,which can meet the temperature requirements of photothermal therapy（PTT）even at very low laser intensity.When the light concentration ratio is 500,the absorbent obtains a high temperature close to 824℃,which can almost meet the performance requirements of the heating device in most photothermal application scenarios.In addition,the main material of the absorber is refractory metal titanium nitride（Ti N）,which has outstanding thermal and chemical stability.The results of this study provide new ideas and experimental basis for the research in the field of photothermal conversion,and have a wide range of application prospects. |
