Enhancing Semi-Transparent Perovskite Solar Cell Efficiency in Harsh Environments with SiO₂/ITO Transparent Contacts and Anti-Soiling Coatings

Indium tin oxide (ITO) thin films remain the cornerstone among transparent conductive oxides (TCOs) for semi-transparent perovskite solar cells (ST-PSCs), where high optical transparency and electrical conductivity are essential for efficient light harvesting and charge transport. However, conventional ITO processing typically requires high-temperature (>200 °C) annealing to achieve sufficient crystallinity, carrier mobility, and film densification. Such thermal dependence restricts their use on heat-sensitive or flexible substrates, posing a major limitation for scalable device integration and next-generation building-integrated photovoltaics (BIPVs). In this study, we demonstrate a room-temperature RF magnetron sputtering approach to fabricate SiO₂/ITO bilayer transparent electrodes with finely controlled structural, optical, and electronic characteristics. The SiO₂ overlayer functions as both a protective and optical-engineering layer, enhancing light transmission, minimizing surface defects, and imparting hydrophilic, anti-soiling behavior, crucial for maintaining optical clarity and stability under real-world environmental exposure. The underlying ITO film, optimized through precise control of sputtering pressure and RF power, exhibits superior crystallinity and uniform grain morphology even without post-deposition annealing. Comprehensive analyses using Hall effect measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) confirm the films’ outstanding quality. The optimized SiO₂/ITO structures deliver an average optical transmittance of ~91% in the 400–1000 nm range, a sheet resistance below 45 Ω sq⁻¹, and a surface roughness under 1 nm, underscoring their excellent trade-off between transparency and conductivity. These results establish a scalable, energy-efficient, and substrate-independent route for producing high-performance transparent electrodes suitable for flexible, semi-transparent perovskite solar cells and other optoelectronic devices, enabling the transition toward low-temperature, sustainable photovoltaic manufacturing.