Liquid Growth Technique Minimizes Perovskite Defects to Boost Solar Cell Efficiency

An international research team has resolved a decade-long bottleneck in renewable energy technology by developing a temporary liquid growth technique for perovskite crystals. The chemical method dramatically reduces atomic-level defects that have historically plagued the promising solar materials. The advance brings highly efficient, printable solar panels closer to commercial reality.[1][2]

Perovskites are synthetic crystals engineered to absorb sunlight and convert it into electricity with remarkable efficiency. Because their precursor ingredients can be prepared as liquids, perovskite solar cells can be manufactured by printing the material in sheets, much like ink on newsprint. This process promises to be cheaper and more sustainable than traditional silicon manufacturing.

However, the rapid crystallization process during printing often creates microscopic structural gaps and scrambled atomic formations at the boundaries between crystal grains. These grain boundary defects act as traps for excited electrons, squandering their captured solar energy as heat before it can be extracted as useful electrical power.[4]

To overcome this limitation, researchers from Sungkyunkwan University, Princeton University, the University of California San Diego, and Argonne National Laboratory introduced a novel chemical mixture during fabrication. They added two specific salts—zinc bromide and methylammonium chloride—to the perovskite precursor ink. This combination fundamentally alters how the crystals assemble.[1][4]

Melting the Boundaries

The two salt additives work synergistically to create a volatile eutectic mixture, which means they melt at a significantly lower temperature when combined than either would alone. Yanqi Luo, a beamline scientist at Argonne National Laboratory, compared the mechanism to spreading salt on an icy road to lower the freezing point of water.[4]

When the perovskite film is gently heated to around 100 degrees Celsius, the eutectic mixture at the grain boundaries briefly transforms into a thin liquid slush. In this temporary liquid state, atoms can diffuse approximately 10,000 times faster than they would in a solid lattice.[1][2]

This accelerated diffusion gives the small crystal grains the necessary room and mobility to rapidly merge, reorganize, and grow into a much more uniform and orderly structure. Rather than freezing into a scrambled formation, the atoms settle into a pristine grid that allows electrons to move freely.[1][2]

As the thermal processing continues, the methylammonium chloride evaporates entirely from the film. Meanwhile, the zinc remains concentrated at the crystal boundaries and interfaces, where it actively helps to passivate and neutralize any remaining electronic defects. The result is a pure, highly ordered crystalline layer.[3]

"We opened up this new class of chemical mixtures that improve the performance of perovskites," said Dane deQuilettes, an assistant professor at Princeton University and senior author of the study published in the journal Science in October 2026. "Energy is living in the material for so long, it broadens what's actually possible with a semiconductor."

Unprecedented Energy Retention

The consequences of this temporary liquefaction are striking at the microscopic level. In the treated, defect-free perovskites, electrons retain the excess energy they absorb from sunlight for up to 300 microseconds. This retention time is roughly ten times longer than what is observed in conventionally processed, untreated perovskite materials.

This extended energy retention translates directly into measurable performance gains across multiple types of optoelectronic devices. In laboratory testing, small-area perovskite solar cells manufactured with the volatile eutectic method achieved a certified power conversion efficiency of 25.9 percent. This places them among the most efficient solar technologies currently available.[2][3]

Crucially, the technique also scales effectively to larger surfaces, which has historically been a major stumbling block for perovskite manufacturing. Larger perovskite minimodules, measuring more than 15 square centimeters in area, reached a power conversion efficiency of 23.9 percent. This consistency over large areas is a mandatory requirement for industrial production.[2][3]

Beyond initial efficiency, the liquid-assisted growth method dramatically improves the long-term durability of the solar cells. When subjected to continuous operation at 85 degrees Celsius, the treated solar cells retained 85.8 percent of their initial efficiency after 1,400 hours. This thermal stability resolves one of the most persistent barriers to commercializing perovskites.[2][3]

Visualizing Atomic Assembly

To confirm exactly how the eutectic mixture was altering the crystal structure, the research team relied on advanced imaging techniques. They conducted extensive experimental analysis using nanoprobe X-ray microscopy at the Advanced Photon Source and the Center for Nanoscale Materials, both located at Argonne National Laboratory.[3][4]

The high-resolution X-ray diffraction allowed the scientists to observe the local melting of the eutectic mixture at the grain boundaries during the annealing process. They witnessed firsthand how the material became disordered and liquid-like during heating, before snapping back into a highly ordered state as the crystal growth concluded.[3][4]

"The breakthrough isn't just about making a better crystal—it's about making a better crystal over a large area, which is the key requirement for real-world manufacturing," said Tao Zhou, a scientist at the Center for Nanoscale Materials who contributed to the structural analysis of the perovskite films.[4]

The researchers also demonstrated that the volatile eutectic approach is highly versatile, working effectively across several different perovskite chemical compositions. This generalizability suggests that the temporary liquid phase could become a standard platform for further innovation and optimization throughout the global photovoltaics research community.

Beyond Traditional Solar

While the primary focus remains on renewable energy generation, the flawless crystals produced by this method have immediate applications in other technologies. Light-emitting diodes (LEDs) manufactured using the exact same liquid-assisted growth process achieved an impressive external quantum efficiency of 26.1 percent, alongside brighter output and longer operational lifetimes.[1][2][4]

In the solar sector, these high-quality perovskites are increasingly being paired directly with traditional silicon to create tandem solar cells. By layering a thin coat of the engineered perovskite over a standard silicon solar cell, manufacturers can create a combined device that captures a much broader spectrum of sunlight.

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These tandem configurations can generate approximately 40 percent more power than a solar cell made from silicon alone. By erasing the performance-limiting defects in the perovskite top layer, the new chemical mixture could translate into a critical one percent overall gain in power generation for these cutting-edge tandem modules.

"Defects have been the bottleneck for perovskites for almost a decade," noted Yanqi Luo. "If we can remove the major defects, we can finally start building devices that last longer and perform more reliably." The advance provides a clear chemical roadmap for moving perovskites out of the laboratory.[2][4]

The Path to Commercialization

Despite the impressive laboratory metrics, transitioning this chemical process to industrial-scale roll-to-roll printing will require further engineering. Manufacturers must ensure that the precise evaporation rates of the salt additives can be tightly controlled in open-air factory environments, rather than just inside specialized nitrogen-filled gloveboxes.

The research team is currently exploring additional eutectic chemistries to see if other salt combinations might yield even lower melting points or faster processing times. Identifying the optimal mixture could further reduce the energy required to manufacture the panels, enhancing the overall carbon footprint of the production cycle.

As global demand for clean electricity accelerates, the ability to rapidly print highly efficient, defect-free solar panels could fundamentally alter the renewable energy landscape. By turning a solid-state problem into a temporary liquid solution, materials scientists have unlocked the latent potential of the world's most promising solar material.[1][4]