Researchers Develop Biodegradable Solar Cell for Agricultural Use

Finland's VTT Technical Research Centre has developed a biodegradable solar cell that is thin, lightweight, and flexible enough to be attached directly to plant stems or large leaves, aiming to support sustainable agriculture and environmental monitoring.

Roughly the size of a credit card, the ultra-thin solar cell decomposes naturally after use, including its rechargeable power source. This makes it particularly suitable for agricultural environments, where retrieval of such devices after deployment can be difficult, the researchers said.

“When used in agriculture, biodegradability is essential. If the cell is not recovered from the field, it causes no harm and does not release hazardous substances or microplastics,” said Maria Smolander, Research Team Leader at VTT.

The innovation is part of a three-year international research initiative involving six institutions, including Tampere University, the University of Glasgow, Poland’s Łukasiewicz Institute of Microelectronics and Photonics, Switzerland’s CSEM, and McGill University in Canada. The project is backed by CHIST-ERA and national funding agencies such as Finland’s Research Council.

The project’s broader goal is to make electronics more environmentally sustainable. “While agriculture is the test bed, the overarching aim is to rethink how electronics are made,” said Liisa Hakola, Senior Scientist at VTT.

VTT developed the solar cell, while Tampere University created a battery-like supercapacitor for energy storage. The consortium also developed compostable sensors and modules that wirelessly transmit environmental data.

“These sensors are not designed to harvest large amounts of energy. They are intended for low-power applications where short-term monitoring is sufficient,” said Marja Välimäki, Senior Scientist at VTT. “The focus is on real-time environmental sensing, not on long-term durability.”

The solar cell comprises a bio-based thin film with a partly inorganic structure and is less than 35 micrometres thick. Even with protective layers, the total thickness remains under a fraction of a millimetre. The lifespan of the cell, which naturally decomposes within weeks or months depending on conditions, can be adjusted using protective coatings.

Developing the biodegradable cell presented unique challenges. “The materials must resist heat and moisture just long enough to fulfill their function. The sensors must also be light enough to be mounted on plants without harming them,” said Hakola.

As environmental regulations tighten, especially in the European Union, farms are under increasing pressure to collect accurate and frequent data on soil nutrients, emissions, and plant health. Real-time, biodegradable sensors powered by compostable solar cells could help meet these requirements more sustainably.

VTT is also working on environmentally friendly electronics and solar cells in a broader EU-funded IoT project focused on merging sustainable technology with circular economy principles.