A new stretchable organic solar cell may offer the efficient power needed for the next generation of wearable devices, according to a team of international researchers.
Led by Zhenye Wang, a researcher at the Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, in Wuhan, China, the team’s work addresses one of the most significant challenges facing wearable technology: developing a durable, flexible, and efficient power source.
Wearable devices must be both flexible and durable to remain unobtrusive during use, bending and stretching along with the body. At the same time, these devices require highly efficient power sources to operate sensors, displays, and transistors without adding unnecessary bulk or weight. Traditional batteries fall short of these requirements because their rigid, static structure limits the flexibility and durability of the devices they power.
The research team tackled these challenges by developing a new type of organic solar cell (OSC). These lightweight, flexible power sources can be processed in solution, making them ideal for wearable technology. While OSCs have long been considered a promising option, creating a practical, high-performance version that maintains efficiency under severe deformations has proven difficult.
A Solar Cell For Wearable Technology
The team developed an innovative solution by combining an organosilane-functionalized small-molecule acceptor (BTP-Si4) with a flexible polymer donor (PNTB6-Cl). This blend demonstrated excellent flexibility and performance.
“This was dicated by the unique twisted/wavy conformation of PNTB6-Cll which enhances ductility and the presence of a silicon atom in the branched substituents of BTP-Si4 which plasticizes the blend,” co-author Antonio Facchetti of Georgia Institute of Technology/Northwestern University explained to The Debrief.
Meeting New Performance Standards For Solar Cells
The stretchable solar cell retains 80% of its efficiency even under extreme strain, outperforming previous attempts at creating stretchable cells. The cell can stretch approximately three times farther than earlier designs while maintaining its functionality.
The team’s findings highlight how the molecular structure and miscibility (the ability of two substances to mix into a uniform blend) of materials directly impact the mechanical flexibility and efficiency of solar cells. This research provides valuable insights into minimizing the trade-off between flexibility and performance.
One of the team’s main challenges was designing the new acceptor, a molecule that facilitates charge transfer. “At the fundamental level, the major challenge was to demonstrate the broad applicability of the molecular design of this new acceptor family and how they operate in plasticizing the blend,” Facchetti explained.
Moving Solar Cells Forward
The team continues their work in the wearable technology space, with an eye on “integrating mechanically robust, ductile power sources with stretchable circuits, sensors and other IoT devices for health care applications,” Fachetti said.
Future steps include “monolithic integration of this type of power source and applicability to other types of semiconductors used, for instance, in transistors and thermoelectric applications,” Facchetti added.
The team’s new paper, “Mechanically Robust and Stretchable Organic Solar Cells Plasticized by Small- Molecule Acceptors,” appeared on January 24, 2025 in Science.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.