Bioinspired Broadband Omnidirectional Anti‐Reflective Coatings by Scalable Dip‐Coating Process for Efficient Solar Energy Collection

ABSTRACT The interface reflection loss severely constrains the light‐harvesting efficiency in solar technologies. Conventional anti‐reflective coatings face limitations such as narrow wavelength, angular dependence, and complicated fabrication process. Here, we propose an omnidirectional light‐harvesting biomimetic design based on refractive index tunable core‐shell particles. The carboxyl groups‐containing polymers aggregate into nanocluster as the core and tetraethyl orthosilicate hydrolyzes into SiO 2 shell. The gradient refractive index of core‐shell particles can be achieved by regulating the composition of core and shell, as well as the pH value during the hydrolysis process. The broadband omnidirectional anti‐reflection (BOAR) coating can be prepared by a scalable dip‐coating process, providing flexibility for the adaptation of different substrates. The BOAR coating has an average transmittance of over 80% across a broad spectral range of 300–2500 nm and a wide incidence angle range of 0 °‐ 85 °. Compared to bare cells, the solar cells with BOAR coating show a 2.5 mA cm −2 increase in short–circuit current density and an improvement in power conversion efficiency from 10.8% to 11.8%. Our work provides a scalable approach that integrates broadband angular stability, omnidirectional performance, and ambient temperature processability, making it suitable for applications in photovoltaic modules, solar energy collectors, and optical devices.