New measurement strategy for OPV

National Institute of Standards and Technology (NIST) has shared that it is making progress with a new class of “economically viable solar power cells”.

According to NIST, scientists have deepened their understanding of the complex organic films.

NIST’s David Germack said currently the industry believes that if these cells can exceed 10% efficiency and 10,000 hours of life, technology adoption will really accelerate. But, according to him, to improve them, there is critical need to identify what’s happening in the material.

“And at this point, we’re only at the beginning,” said Germack.

The NIST team has come up with a measurement strategy for organic photovoltaics that reveals ways to control how they form. It underlined that in the most common class of organic photovoltaics, the “ink” is a blend of a polymer that absorbs sunlight, enabling it to give up its electrons, and ball-shaped carbon molecules called fullerenes that collect electrons. By applying X-ray absorption measurements to the film interfaces, the team discovered that by changing the nature of the electrode surface, it will repulse fullerenes (like oil repulses water) while attracting the polymer. The electrical properties of the interface also change dramatically. The resultant structure gives the light-generated photocurrent more opportunities to reach the proper electrodes and reduces the accumulation of fullerenes at the film bottom, both of which could improve the photovoltaic’s efficiency or lifetime.

NIST has identified some key parameters needed to optimise what happens at both edges of the film, which means the industry will have a strategy to optimise the cell’s overall performance.

“Right now, we’re building on what we’ve learned about the edges to identify what happens throughout the film. This knowledge is really important to help industry figure out how organic cells perform and age so that their life spans will be extended,” said Germack.