Optimized amorphous TiO ₂ –SiO ₂ multilayer antireflective coatings for possible improvement in silicon-based solar cell performance

Antireflection coatings (ARCs) are essential for reducing optical losses and improving light coupling in silicon (Si)-based solar cells. In this study, sol–gel spin-coated single-, double-, and triple-layer ARC structures are made up of TiO 2 , TiO 2 −SiO 2 mixed layers, and SiO 2 on Si substrates and are systematically investigated. X-ray diffraction was used to confirm the phase of the deposited thin films, revealing that all three layers are amorphous, as no sharp diffraction peaks were observed. Spectroscopic ellipsometry (SE) was employed to determine the film thickness and the wavelength-dependent refractive index (n) along with the extinction coefficient (k), which are critical parameters for optical modeling. The optical reflectance of the ARC/Si structures was measured, for uncoated, single-, double-, and triple-layer structures, and the effective incident photon flux at the Si surface was calculated. Using the calculated incident photon flux, the maximum achievable short-circuit current density ( J sc ) was estimated under standard AM1.5G solar illumination. The results reveal an increase in optical transmission and J sc with an increasing number of ARC layers, attributed to improved refractive index grading and increased light transmission over a broader spectral range. Among all the studied structures, the triple-layer ARC exhibits the highest enhancement in maximum possible J sc , demonstrating its potential for improving optical performance in Si-based solar cell applications.