In recent years, scientists have been trying to find a way to improve the efficiency of organic photovoltaic cells. Some researchers have even thought that organic solar cells may never improve beyond 15 percent. Solar cells based on silicon, by comparison, are in the 18 to 22 percent range.
But in a new effort, the researchers in China have developed an organic photovoltaic cell that converts 17.3% of the energy in sunlight into electricity.
“Organic solar cells have been studied for many years, but they’re still relatively young compared to silicon,” said Chen Yongsheng, a chemist at Nankai University in North China’s Tianjin. “We still don’t understand their device performance very well.”
Chen’s group used tandem cells, which are put together by different layers of organic materials. Previous designs for tandem organic cells have failed to tap into the abundant solar energy of the near-infrared range, but Chen’s team addressed this issue.
They used a non-fullerene acceptor molecule known as O6T-4F, which was able to work better at this wavelength. They then combined that with a layer containing a relatively new electron acceptor, called F-M for short, which the team had earlier developed. This material was shown to be an excellent match for its electrical properties and could absorb visible light.
“Different layers of the tandem cells can absorb different wavelengths of light. That means you can use sunlight in the wider wavelengths more efficiently and achieve a higher power conversion rate,” Dr. Chen Yongsheng said.
“There’s no reason why an organic solar cell can’t have a similar or higher performance to silicon or perovskites,” according to Chen.
The breakthrough is published in the journal Science