Scalable Aluminum-Doped Zinc Oxide Transparent Electrodes via Spatial ALD for High-Efficiency Perovskite Modules

Large-area commercialization of perovskite solar modules remains limited by cost and scarcity of indium-based transparent electrodes. Here, we report a scalable aluminum-doped zinc oxide (AZO) fabricated by spatial Atomic Layer Deposition (ALD) that achieves record electrical performance through atomic-level dopant regulation. By controlling the Al:Zn cycle ratio, Al incorporation within 2.4%-4.2% was precisely tuned to optimize conductivity. Systematic experiments and calculations reveal that low Al concentrations favor substitutional incorporation, increasing carrier, while higher concentrations induce interstitial defects that contribute to carrier and enhance scattering, defining an optimum doping window. The AZO exhibits a sheet resistance of 3.3 Ω sq^-1, lower than commercial indium tin oxide (ITO, 5.8 Ω sq^-1), with 90% transmittance and 55% haze. Spatial ALD ensures uniform deposition across 900 cm² substrates (2.36% thickness variation, 4.62% sheet-resistance variation), enabling 18.50% efficiency in large-area modules, the highest reported to date. This approach offers a manufacturing-compatible route toward indium-free, high-conductivity electrodes for scalable devices.