A Lead-Based Surface Treatment Pushes Perovskite Solar Modules Toward Industrial Scale

Perovskite solar cells have spent the past decade moving from laboratory curiosity to one of the most closely watched technologies in renewable energy. Their appeal comes from an unusual combination of properties: perovskite semiconductors can absorb sunlight extremely efficiently, can be processed from solution, and may be manufactured using comparatively low temperatures and lightweight materials. Yet the same surfaces that help these devices achieve high efficiencies can also become their greatest weakness. Now, a team led by researchers including D. Xu, K. Xiao and Y. Liu reports a strategy designed to address one of the most persistent obstacles to commercial-scale production: achieving reliable surface passivation during the fabrication of meter-scale modules in ordinary air.

The work, published in Nature, replaces humidity-sensitive ammonium halide passivators with chemically stable lead carboxylates. Surface passivation is a crucial step in perovskite photovoltaics because imperfections at the boundary of the perovskite layer can trap charge carriers, accelerate recombination and reduce the voltage and current extracted from a solar cell. In a well-passivated device, these defects are chemically neutralized or electronically controlled, allowing photogenerated electrons and holes to travel toward their respective contacts more efficiently. Ammonium halides have become popular for this purpose because they can modify the perovskite surface and improve device performance, but they are vulnerable to moisture and can be difficult to distribute uniformly over large areas.

That difficulty becomes especially serious when the coating process is expanded from a small laboratory sample to a solar module measuring hundreds of square centimetres. In slot-die coating, a liquid precursor is continuously deposited through a narrow coating head and spread across a moving substrate. The method is compatible with industrial manufacturing, but it also makes the uniform application of a separate surface-treatment solution more complicated. Variations in wetting, drying speed, local concentration and solvent evaporation can leave some regions over-treated and others insufficiently passivated. Under humid ambient conditions, ammonium halides may also absorb water or undergo chemical changes, forcing manufacturers to use inert atmospheres that increase equipment complexity and production cost.

The researchers approached the problem by engineering the perovskite film itself before applying the passivator. They used a high-saturation-vapor-pressure solvent system composed of 2-methoxyethanol, 1,3-dioxolane and dimethyl sulfoxide. During film formation, this solvent combination helps control the crystallization process and produces a surface naturally enriched in formamidinium iodide. Formamidinium is an organic cation used in many high-performing perovskite compositions, while iodide is one of the key halide components that determines the semiconductor’s structure and electronic behavior. Creating this tailored surface provides a chemical environment intended to interact favorably with the subsequent lead carboxylate treatment.

The selected passivator was lead dioleate, a lead-containing compound associated with oleate chains. According to the study, applying lead dioleate to the formamidinium iodide-enriched surface serves two functions at once. It helps suppress electronic defects at the perovskite interface, reducing pathways through which carriers can recombine before reaching the electrodes. At the same time, the treatment enhances carrier transport across the surface region. This dual action is important because a passivation layer that blocks defects but also impedes charge movement could limit the overall benefit. The researchers’ design instead aims to create an interface that is both electronically cleaner and more conductive.

The chemistry is particularly relevant to large-area manufacturing because the lead carboxylate treatment is described as more stable than conventional ammonium halides under humid conditions. Stability does not eliminate the need for careful process control, nor does it resolve every environmental question associated with lead-containing photovoltaic materials. However, it could reduce the sensitivity of the passivation step itself and make it more compatible with ambient processing. In principle, a robust surface treatment could allow manufacturers to coat and handle larger substrates without maintaining the entire production line inside a rigorously controlled inert environment.

The resulting performance was demonstrated at module scale rather than only on small research cells. The team fabricated perovskite solar modules with a certified efficiency of 24.0 percent measured over an aperture area of 810 square centimetres. They also achieved a certified efficiency of 22.0 percent for a device with a total area of 0.72 square metres. The distinction between aperture area and total area matters: aperture efficiency measures the active opening through which light reaches the device, while total-area efficiency accounts for the entire module footprint, including spaces occupied by interconnections and inactive regions. Maintaining high performance across such large areas is substantially more difficult than producing a record result on a tiny cell.

Large-area modules must also overcome electrical losses that are less prominent in small devices. A module is constructed from many interconnected subcells, and each connection introduces potential resistance, alignment errors and non-uniform current flow. Defects that affect only a small part of a laboratory cell can become significant when repeated across a large substrate. By improving both surface passivation and carrier transport, the lead dioleate strategy is intended to reduce losses at the perovskite interface while supporting uniform operation across the module. The reported results indicate that the chemical treatment remained effective even when translated into a manufacturing-relevant architecture.

Performance under standard operating conditions is only one measure of whether a solar technology is ready for deployment. Perovskite devices have historically faced concerns involving moisture, heat, illumination, electrical bias and mechanical or processing-induced degradation. The researchers report that their modules passed all reliability tests specified by IEC 61215, the international standard used to evaluate the durability and design qualification of terrestrial photovoltaic modules. Passing these tests does not mean that every possible lifetime or field condition has been eliminated as a concern, but it represents a major benchmark for a technology that has often been judged by short-term laboratory efficiency rather than long-duration reliability.

The study’s significance therefore extends beyond a single record-setting number. It presents a manufacturing strategy in which the surface chemistry of the perovskite is deliberately prepared during deposition and then matched with a stable carboxylate-based passivator. That approach could help bridge the gap between highly optimized laboratory cells and industrially relevant modules made by continuous coating. The authors describe the reported efficiencies as the highest achieved for scalable, industrially viable perovskite photovoltaics. If the method can be reproduced consistently across larger production lines and maintained over long operating lifetimes, it could strengthen the case for perovskite modules as a practical complement to established silicon solar technology. For now, the results offer a compelling demonstration that controlling a few molecular layers at a solar cell’s surface can influence the performance and reliability of an entire meter-scale power-generating device.

Subject of Research: Large-area perovskite solar modules, surface passivation, ambient-compatible photovoltaic manufacturing and lead carboxylate interface engineering

Article Title: Lead carboxylates passivation for meter-scale perovskite solar modules

Article References: Xu, D., Xiao, K., Liu, Y. et al. Lead carboxylates passivation for meter-scale perovskite solar modules. Nature (2026). https://doi.org/10.1038/s41586-026-10994-7

Image Credits: AI Generated

DOI: 10.1038/s41586-026-10994-7

Keywords: Perovskite solar cells, perovskite solar modules, lead dioleate, lead carboxylates, surface passivation, formamidinium iodide, slot-die coating, ambient manufacturing, scalable photovoltaics, IEC 61215, solar energy, photovoltaic reliability

Tags: charge carrier recombination reductiondefect passivation in perovskite photovoltaicshumidity-resistant passivation strategiesindustrial-scale perovskite solar cell productionlead carboxylates for perovskite modulesmeter-scale perovskite module efficiencypassivation layer stability in perovskite modulesperovskite solar cell surface passivationscalable perovskite solar module fabricationsolution-processed perovskite solar cellsstable lead-based surface treatments