High-Performance Spectrally Selective Absorber Using the ZrB₂-Based All-Ceramic Coatings

Current solar energy conversion systems face limitations due to the spectral selectivity and thermal stability of absorber materials. While optical films offer potential, their performance under high temperatures remains a challenge. Prior research has shown that ceramic coatings can withstand extreme conditions, but their integration into spectrally selective designs is limited. This gap motivated the development of new materials that combine high optical performance with thermal resilience. Existing studies focus on cermet-based systems but lack the microstructural optimization needed for high solar absorptance. The need for materials that maintain efficiency at elevated temperatures remains unmet. No prior work had resolved the balance between optical absorption and thermal endurance in ceramic-based solar absorbers. This paper introduces a novel approach using quasioptical microcavity structures to enhance performance.

The goal of this research is to develop a spectrally selective absorber with high solar absorptance and thermal stability for concentrated solar power systems. The specific problem addressed is the limitation of current absorber materials in maintaining performance at high temperatures. The motivation stems from the need to improve energy conversion efficiency in solar power systems. The study aims to design an all-ceramic coating that combines optical and thermal advantages. The focus is on using ZrB₂-based materials to achieve both high absorption and durability. The approach involves integrating a quasioptical microcavity structure to enhance spectral performance. This design is intended to outperform existing absorber materials in both efficiency and thermal resilience. The study seeks to demonstrate a viable alternative to conventional absorber technologies.

The researchers designed a ZrB₂-based all-ceramic coating with a quasioptical microcavity (QOM) structure. The QOM was engineered to enhance multiabsorption mechanisms through intrinsic cermet absorption, surface plasmon polaritons, and localized surface plasmon resonance. The design was analyzed using electromagnetic power loss simulations to validate the absorption mechanisms. The structure was optimized to ensure impedance matching with free space in the solar spectrum range. The thermal stability of the coating was tested at 800 °C in vacuum and 500 °C in air for 200 hours. The performance was evaluated based on solar absorptance and thermal endurance metrics. The materials were selected for their high-temperature resistance and optical properties. The study combined theoretical modeling with experimental validation to confirm the effectiveness of the design.

The ZrB₂-based all-ceramic absorber achieved a solar absorptance of 0.965, demonstrating excellent performance. The high absorptance was attributed to the quasioptical microcavity structure, which enabled multiple absorption mechanisms. The design supported intrinsic cermet absorption, surface plasmon polaritons, and localized surface plasmon resonance. Electromagnetic power loss simulations confirmed the effectiveness of these mechanisms in enhancing absorption. The structure also ensured impedance matching with free space in the solar spectrum range. The absorber maintained its performance at 800 °C in vacuum and 500 °C in air for 200 hours. The thermal stability was attributed to the use of ultrahigh-temperature ceramic ZrB₂ and the QOM structure. The system's total conversion efficiency reached approximately 67% under 800 °C and 1000 suns.

The study demonstrated that the ZrB₂-based all-ceramic absorber with a quasioptical microcavity structure offers high solar absorptance and thermal stability. The authors propose that the QOM structure enhances absorption through multiple mechanisms, including cermet absorption and plasmonic effects. The thermal endurance of the absorber is attributed to the properties of ZrB₂ and the microcavity design. The results suggest that the structure can maintain performance at high temperatures, making it suitable for concentrated solar power systems. The authors suggest that the absorber's efficiency could reach 67% under ideal conditions. The findings support the use of ZrB₂-based materials in high-performance solar absorbers. The study highlights the importance of structural design in achieving optimal spectral selectivity. The authors conclude that the proposed design represents a significant advancement in solar absorber technology.