High-performance Al2O3 sol–gel films: Improving solar cell efficiency through antireflective and superhydrophobic properties

Abstract

This study developed a multifunctional aluminum oxide

film combining anti-reflective and superhydrophobic properties for enhanced photovoltaic (PV) performance in outdoor applications. The film was created on glass substrates using a sol–gel, dip coating, and controlled etching process, resulting in a porous surface with grass-like nanostructures. After 512 s of etching, the film achieved a roughness of 23.63 nm and a refractive index of 1.14 at 550 nm. It demonstrated excellent broadband anti-reflection, with 96.86% average transmittance and 3.07% reflectance across the 350–1500 nm spectrum, peaking at 99.30% transmittance at 480 nm. The film maintained over 90% transmittance at angles up to 45°, providing omnidirectional functionality crucial for solar panels. Its superhydrophobicity (162.3°water contact angle and hysteresis 7.5°) ensures self-cleaning. When applied as a solar cell cover glass coating, the film enhanced short-circuit current density and power conversion efficiency. A 19.19% efficiency increase was observed at a 60°incidence angle, demonstrating the film’s potential for significant PV performance improvement.