Osaka Metropolitan University Breakthrough Delivers Lead-Free Piezoelectric Films with Record Energy Harvesting Performance

Osaka Metropolitan University develops record-breaking lead-free piezoelectric films on silicon, boosting vibration energy harvesting efficiency fivefold.

By: AXL Media

Published: Mar 19, 2026, 5:56 AM EDT

Source: Information for this report was sourced from Osaka Metropolitan University

Revolutionizing Sustainable Energy Harvesting in Electronics

Scientists at Osaka Metropolitan University have achieved a major milestone in the development of environmentally friendly electronics by creating high-performance piezoelectric thin films that do not rely on toxic lead. While piezoelectric materials are already ubiquitous in devices like microphones and headphones, the most efficient versions have historically utilized lead, posing significant environmental risks. The new research focuses on bismuth ferrite, a lead-free alternative that has previously been sidelined due to high electrical leakage and low energy conversion rates, now transformed through advanced molecular engineering.

Mastering the Challenge of Silicon Compatibility

The primary technical hurdle in this development was the inherent incompatibility between bismuth ferrite and standard silicon wafers used in semiconductor manufacturing. While compressive strain typically enhances the properties of these films, silicon wafers exert a tensile pull during the cooling process, which usually degrades performance. Lead researcher Takeshi Yoshimura explained that instead of fighting this physical tension, the team strategically utilized the strain to trigger a structural phase transition, successfully turning a manufacturing obstacle into a performance-enhancing advantage.

Accelerated Optimization Through Combinatorial Sputtering

To identify the precise conditions required for this transition, the team pioneered a "biaxial combinatorial sputtering" technique. This method allowed researchers to vary growth temperatures and chemical compositions continuously across a single wafer, effectively testing dozens of variables simultaneously. This approach bypassed years of traditional trial-and-error experimentation, allowing the team to pinpoint the exact moment the material shifts from a rhombohedral to a monoclinic crystal phase, which is the state required for peak electronic efficiency.