X-ray nanotomography aids the production of eco-friendly solar cells

Polymer solar cells are in the spotlight for sustainable energy production of the future. Among the challenges to realize this, their production needs to become efficient and reliable while avoiding the use of chemicals which are harmful for the environment. Because the relevant structures in solar cell devices are as small as a few tens of nanometers or, equivalently, a thousand times smaller than a human hair, their visualization without destroying the entire layered structure of the device remains a challenge even for the most advanced imaging techniques using electron microscopy. Yet this characterization is crucial for identifying the failure mechanisms in the developing of mass-production and environmentally friendly organic solar cells. Scientists from the Technical University of Denmark in collaboration with PSI researchers have recently exploited the unique capability of non-destructive three-dimensional imaging with nanometer resolution offered at the Swiss Light Source to visualize a complete tandem solar cell device including layers coated from solutions of nanoparticles in water that convert solar energy to electricity. By analyzing the resulting three-dimensional images, the failure mechanism of the device was identified and improved performance was demonstrated by alternative fabrication routes.