Systematic Optimization of Sputtered AZO Thin Films and Their Integration as Alternative Transparent Electrodes for Perovskite Solar Cells

Transparent conducting oxides (TCOs) are critical components of perovskite solar cells (PSCs), motivating the search for low-cost and scalable alternatives to conventional fluorine-doped tin oxide (FTO). Among the proposed alternatives, Al-doped ZnO (AZO) has been widely investigated as a low-cost, indium-free transparent conductive oxide. However, systematic studies correlating sputtering parameters with AZO thin film properties and PSC performance through direct benchmarking against commercial FTO under identical device fabrication conditions remain limited. In this study, AZO thin films were systematically optimized by magnetron sputtering through controlled variation of sputtering power, annealing conditions, substrate temperature, and deposition duration. The optimized high-temperature-grown AZO film (AZO-13) exhibited high visible transparency (∼86%), low sheet resistance (1.26 × 101 Ω·sq–1), strong preferential (002) orientation, and high calculated electrical conductivity (∼9.85 × 102 S·cm–1), achieving a Haacke figure of merit (0.668) that slightly surpassed that of commercial FTO (0.664). To evaluate its applicability as a transparent electrode, the optimized AZO film was directly integrated into PSC devices and compared with commercial FTO under identical fabrication conditions. The AZO-based PSC achieved a stabilized efficiency of 16.49%, while comparative PL/TRPL, EQE, and EIS analyses revealed that the lower device performance mainly originated from increased interfacial resistance and less efficient charge extraction. In addition, AZO exhibited improved long-wavelength transparency compared with FTO, suggesting potential relevance for tandem-oriented photovoltaic applications. These results establish a clear process–structure–property–device relationship for sputtered AZO thin films and demonstrate their potential as alternative TCO electrodes for PSC technologies.