Researchers from Wake Forest University, SUNY University at Buffalo and Technical University of Dresden have addressed the issue of perovskites' susceptibility to environmental degradation and reliance on toxic solvents in traditional processing methods, by introducing methylammonium lead iodide (MAPbI3) perovskite films that are processed via a solvent-free laser printing technique. The films produced using this method reportedly exhibit exceptional stability and can withstand extreme conditions.
Instead of using solvents, the team created a dry powder by combining methylammonium lead iodide (the perovskite semiconductor) with carnauba wax and microscopic silica particles. Using a modified laser printer, they deposit this powder in precise patterns. The laser's heat briefly melts the mixture, allowing it to reform into a layered structure.
Detailed microscope analysis found why this printing method produces such stable materials. When the laser melts the powder, the wax and silica naturally separate from the perovskite due to their different chemical properties - like oil separating from water. As the material cools, the perovskite forms crystals surrounded by a protective shell of wax and silica. This self-organized structure forms automatically during printing, requiring no additional manufacturing steps.
The researchers subjected their printed materials to conditions that typically destroy perovskites within minutes. The films maintained 90% of their electrical conductivity after exposure to X-ray radiation doses of 200 Gy - equivalent to several years of exposure in low Earth orbit and far beyond what conventional electronics can withstand. Under extreme humidity (90% relative humidity, compared to typical indoor levels of 30-50%), the printed materials showed only minor degradation after five hours, while conventional perovskite films failed completely within minutes. Even at temperatures of 80 °C, hot enough to cause rapid degradation in normal perovskite devices, the printed versions maintained stable performance for over five hours.
The current trade-off for this exceptional stability, however, is reduced electrical performance. The printed materials show about one-tenth the electrical conductivity of conventional perovskite films because the protective wax and silica components act as electrical insulators. However, this lower conductivity still exceeds the minimum requirements for applications like radiation detectors in medical equipment or solar cells for satellites, where reliable long-term operation matters more than maximum efficiency.
The printing process offers several additional advantages over traditional manufacturing methods. It works in normal air at room temperature, unlike conventional techniques that require controlled atmospheres. The printer can deposit materials in precise patterns as small as 30 micrometers, essential for creating complex electronic devices. Most importantly, it eliminates the need for toxic solvents that make traditional perovskite manufacturing hazardous.
This advance provides a practical solution to the stability problems that have limited perovskite applications.
By creating inherently stable materials through a straightforward printing process, the research establishes a foundation for developing perovskite devices that can operate reliably in real-world conditions. The method's compatibility with standard manufacturing equipment and elimination of toxic solvents could accelerate the commercial adoption of perovskite electronics in applications where environmental durability is critical. So, the study's results highlight the potential of laser printing as a scalable, safe, and sustainable manufacturing route for producing stable perovskite-based devices with potential applications in diverse fields, ranging from renewable energy to large-area electronics and space exploration.
