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

Why It Matters

Replacing scarce, expensive ITO with low‑cost AZO removes a key barrier to commercializing large‑area perovskite modules, accelerating market adoption and reducing supply risk.

Key Takeaways

• AZO electrodes achieve 3.3 Ω/sq sheet resistance, beating ITO
• Spatial ALD delivers uniform 900 cm² films with <3% variation
• Optimal Al doping (2.4‑4.2%) balances conductivity and defect scattering
• 18.5% module efficiency sets new large‑area perovskite record
• Indium‑free electrode cuts material cost and mitigates supply risk

Pulse Analysis

Perovskite solar cells have surged in efficiency, yet their transition to the utility scale hinges on affordable, high‑performance transparent conductive oxides. Indium tin oxide (ITO) dominates the market but suffers from volatile indium prices and limited supply, prompting researchers to explore alternatives. Aluminum‑doped zinc oxide (AZO) offers comparable conductivity and superior optical properties, but achieving uniform, low‑resistance films over square‑meter areas has been challenging. Spatial atomic layer deposition (ALD) resolves this by delivering layer‑by‑layer precision at industrial speeds, enabling consistent dopant incorporation across large substrates.

The study demonstrates that controlling the Al:Zn cycle ratio yields an optimal Al concentration window of 2.4‑4.2%. Within this range, Al atoms preferentially substitute Zn sites, boosting carrier density while minimizing interstitial defects that cause scattering. The resulting AZO films exhibit a sheet resistance of 3.3 Ω/sq—significantly lower than the 5.8 Ω/sq typical of commercial ITO—while maintaining 90% transmittance and 55% haze, ideal for light‑trapping in perovskite stacks. Uniformity metrics show only 2.36% thickness and 4.62% sheet‑resistance variation across a 900 cm² panel, directly translating to an 18.5% power conversion efficiency, the highest recorded for a module of this size.

Beyond the laboratory, these findings could reshape the economics of perovskite manufacturing. An indium‑free, low‑cost AZO electrode reduces material expenses and mitigates geopolitical supply risks, making large‑area roll‑to‑roll production more viable. The compatibility of spatial ALD with existing coating lines suggests a relatively smooth integration path for manufacturers. As the solar industry seeks to diversify its technology portfolio, scalable AZO electrodes may become a cornerstone for next‑generation, high‑efficiency photovoltaic modules.