Structured graphene metamaterial selective absorbers for high efficiency and omnidirectional solar thermal energy conversion

Abstract

An ideal solar-thermal absorber requires efficient selective absorption with a tunable bandwidth, excellent thermal conductivity and stability, and a simple structure for effective solar thermal energy conversion. Despite various solar absorbers having been demonstrated, these conditions are challenging to achieve simultaneously using conventional materials and structures. Here, we propose and demonstrate three-dimensional structured graphene metamaterial (SGM) that takes advantages of wavelength selectivity from metallic trenchlike structures and broadband dispersionless nature and excellent thermal conductivity from the ultrathin graphene metamaterial film. The SGM absorbers exhibit superior solar selective and omnidirectional absorption, flexible tunability of wavelength selective absorption, excellent photothermal performance, and high thermal stability. Impressive solar-to-thermal conversion efficiency of 90.1% and solar-to-vapor efficiency of 96.2% have been achieved. These superior properties of the SGM absorber suggest it has a great potential for practical applications of solar thermal energy harvesting and manipulation.

Transforming silicon into a high performing in tegrated nonlinear photonics platform by integrati on with 2D graphene oxide films

“…No significant change was observed, and the measured output SPM spectra in Figure 6 were repeatable when we reinjected the optical pulses, indicating that the optically induced changes (e.g., loss, n2) of the GO films were not permanent. Note that we previously showed that the material properties of GO can also be permanently changed by femtosecond laser pulses [38][39][40][41] with significantly higher peak powers. This is distinct from the reversible power-dependent changes observed here.…”

“…Among the various 2D materials, GO has received increasing interest due to its ease of preparation as well as the tunability of its material properties [36][37][38][39][40][41]. Previously, we reported GO films with a giant Kerr nonlinearity of about 4 orders of magnitude higher than that of silicon [40,42], and demonstrated significantly enhanced four-wave mixing (FWM) in doped silica waveguides and microring resonators integrated with layered GO films [43,44].…”

Graphene oxide films for advanced ultra-flat optical devices and photonic integrated circuits

“…Ultrafast direct laser writing (DLW) has been widely used as a laser reduction method that is capable of both 2D and 3D writing of arbitrary patterns [41][42][43][44][45][46][47][48]. Ultrashort laser pulses offer low thermal effects that enable high fabrication resolution as well as rich light-matter interaction mechanisms and dynamics.…”

“…The strong light absorption in thin films with a large surface area and the very broad spectral / angular responses are highly desirable for solar thermal applications. A solar-thermal absorber based on 3D structured rGO was reported subsequently [44],…”

“…(a) 90-nm-thick GO gratings for strong and broadband absorption of unpolarized light[48]: (i) schematic of fabrication; (ii) -(iii) measured absorptivity spectra for different incident polarizations and angles, respectively. (b) A selective solar-thermal absorber based on a GO film coated on a metallic trench-like structure[44]: (i) device schematic; (ii) measured and simulated reflectance and absorbance spectra.…”