Spectrum-Selective High-Temperature Tolerant Thermal Emitter by Dual-Coherence Enhanced Absorption for Solar Thermophotovoltaics

Solar thermophotovoltaics (STPV) receive considerable attention for the record high energy transfer efficiency beyond conventional photovoltaics systems, which requires a well-designed structured absorber/emitter and high operating temperature. However, the inherent tradeoff between increased operation temperature and material/structure stability (especially for the thermal emitters) severely hinders the development of STPV. In this work, a new design is proposed for a step-function-like thermal emitter based on a two-path (quasi) coherent perfect absorption effect, which is experimentally enabled by a few-layer Si/Mo/AlN lamellar film on a Mo substrate through a sequential physical vapor deposition process. The as-prepared lamellar emitter exhibits maximal emissivity of ≈97% for 1.4 µm with excellent thermal suppression down to 10% across 3.4–10 µm, the performance of which is well maintained up to 973 K. When employed in the established STPV system, the dual coherent enhanced absorption (DCEA) system contributes to an increase of 20% in the total system efficiency compared to the unimodal coherent perfect absorption counterpart. The design proposed in this study provides a new methodology for improving the efficiency of the STPV system and may have significant applications in improving thermal energy regulation for compact systems.