Solution‐Processed All‐Ceramic Plasmonic Metamaterials for Efficient Solar–Thermal Conversion over 100–727 °C

Low‐cost and large‐area solar–thermal absorbers with superior spectral selectivity and excellent thermal stability are vital for efficient and large‐scale solar–thermal conversion applications, such as space heating, desalination, ice mitigation, photothermal catalysis, and concentrating solar power. Few state‐of‐the‐art selective absorbers are qualified for both low‐ (<200 °C) and high‐temperature (>600 °C) applications due to insufficient spectral selectivity or thermal stability over a wide temperature range. Here, a high‐performance plasmonic metamaterial selective absorber is developed by facile solution‐based processes via assembling an ultrathin (≈120 nm) titanium nitride (TiN) nanoparticle film on a TiN mirror. Enabled by the synergetic in‐plane plasmon and out‐of‐plane Fabry–Pérot resonances, the all‐ceramic plasmonic metamaterial simultaneously achieves high, full‐spectrum solar absorption (95%), low mid‐IR emission (3% at 100 °C), and excellent stability over a temperature range of 100–727 °C, even outperforming most vacuum‐deposited absorbers at their specific operating temperatures. The competitive performance of the solution‐processed absorber is accompanied by a significant cost reduction compared with vacuum‐deposited absorbers. All these merits render it a cost‐effective, universal solution to offering high efficiency (89–93%) for both low‐ and high‐temperature solar–thermal applications.