A comprehensive review of granular structures as photothermal absorber materials

Light trapping is a popular method used to improve the performance of photothermal absorbers. Granular structures are one of the light-trapping structures currently developed. In this paper, a review on the working principle and types of granular structures is presented. Furthermore, recent findings pertaining to the innovations of granular structures as photothermal absorber materials are discussed. This paper presents the extent of research and development in this area and identify the potential of granular structures as photothermal absorbers. The performance metrics used to evaluate the performance of photothermal absorber materials are described, which will be useful as a reference for making valid and reliable measurements. Moreover, this paper presents the material properties, types of fluid flow, and energy loss management that need to be considered when analyzing the performance of photothermal absorbers, which will serve as a reference for scientists and engineers for future sustainable technology development.