Low-cost and high-performance ITO/ZnO/ITO multilayer structure for silicon heterojunction solar cells

Transparent conducting oxides (TCOs) are critical for effective light transmission and charge collection in silicon heterojunction (SHJ) solar cells. While indium tin oxide (ITO) remains the standard choice, its high cost and material scarcity have motivated the search for alternative or complementary materials. Zinc oxide (ZnO), known for its wide bandgap and chemical stability, has emerged as a promising candidate. In this study, an ITO/ ZnO/ITO multilayer structure is proposed as a cost-effective and efficient alternative to conventional single-layer TCO configurations in SHJ solar cells. Using OPAL-2 optical simulations and experimental fabrication via magnetron sputtering, the trilayer design demonstrated enhanced light absorption, reduced surface reflectance, and improved charge transport properties. Importantly, the structure achieved a power conversion efficiency (PCE) of 18.5 %, representing a 6 % and 11 % relative improvement over ITO-only and ZnO-only configurations, respectively, while reducing ITO consumption by approximately 14 %. These results highlight the potential of ITO/ZnO/ITO multilayers to optimize device performance and lower material costs, offering a practical pathway toward more sustainable SHJ solar cell technologies.