Flexible, Radiation-Resistant Organic Solar Cells Ideal for Space Exploration, New Study Finds

Organic solar cells have emerged as a promising solution for powering space missions due to their lightweight, flexible, and radiation-resistant properties. These solar cells, made from carbon-based materials, are being explored as alternatives to traditional silicon and gallium arsenide cells. Both silicon and gallium arsenide, while effective, are costly, heavy, and lack flexibility. Organic solar cells, on the other hand, demonstrate resilience against high-energy protons, which are among the most damaging particles encountered in space.

Radiation Resistance of Organic Solar Cells

According to a study published in Joule, organic solar cells constructed with small molecules showed no degradation in performance after being subjected to radiation equivalent to three years of space exposure. However, those made with polymer-based materials experienced a 50 percent drop in efficiency. This reduction was attributed to the formation of electron traps when protons cleaved molecular side chains, preventing electrons from flowing to the electrodes.

Stephen Forrest, Peter A. Franken Distinguished University Professor of Engineering at the University of Michigan, explained to TechExplore that the damage could potentially be reversed by thermal annealing. Heating the cells to approximately 100 degree Celsius in a laboratory setting enabled the hydrogen to re-bond with carbon atoms, repairing the molecular structure. However, questions remain about the reliability of this process in the vacuum of space or under prolonged mission conditions.

Future Research Directions

The study's lead author, Yongxi Li, an associate research scientist in electrical and computer engineering at the time, highlighted to TechExplore that further exploration would focus on preventing the formation of electron traps or developing materials capable of self-healing. With Li transitioning to Nanjing University, research is expected to continue on advancing organic solar cells for space applications.

The research was conducted at facilities including the Lurie Nanofabrication Facility and the Michigan Ion Beam Laboratory. While challenges remain, the findings open new possibilities for improving the efficiency and durability of solar cells in the demanding environment of space exploration.