Fabrication of robust liquid-like coatings integrating down-shifting, anti-reflection, and anti-smudge multifunction

Solar energy is green and abundant, and solar cells are essential to realizing carbon neutrality. However, their power conversion efficiency (PCE) is greatly impacted by energy losses brought about by surface pollution, spectrum mismatch, and reflection. In the current work, robust liquid-like, down-shifting, and anti-reflective DSL/DT coatings were developed by a novel design for the first time. The down-shifting layer (DSL) is composed of CaMoO 4 : Eu 3 + nanocrystals, ZnO nanoparticles (ZnO NPs), and acid-catalyzed silica sol (ACSS), which can absorb and convert harmful UV energy (200–400 nm) into harvestable visible light (400–800 nm). On top of the DSL, a highly transparent liquid-repellent layer (DT) was created in situ utilizing diethoxydimethylsilane (DEDMS) and tetraethyl orthosilicate (TEOS) as precursors. The DSL/DT coating has liquid-like characteristics as a result of polydimethylsiloxane (PDMS) flexible chains that are enriched on the coating surface. A gradient refractive index is achieved by the double-layer structure, which enhances the light transmittance of coated glass (T max =91.5 %) to 94.9 % in the wavelength range of 400–1100 nm. Furthermore, the three-dimensional network formed by Si-O bonds provides significant mechanical strength, with a pencil hardness of at least 8 H and an adhesion rating of 5 A. The coating also displays UV/sunlight/chemical stability, and could withstand water falling, sand impacting and 3 M tape peeling. The DSL/DT double-layer structure successfully overcomes the limitations of current down-shifting coatings that cannot meet the comprehensive performance requirements for practical scenarios, achieving multi-function integration, high transmittance and mechanical strength and representing a notable progress in the field of down-shifting coatings, and therefore opens a new avenue to the design and fabrication of multifunctional coatings of mitigated contamination and sustained performance suitable for solar panels.