Scientists have set a new world record by creating low-cost, high-efficient and fullerene-free polymer solar cells using a unique combination of polymer. Fullerenes are usually required in polymer solar cells to separate charge carriers in order to obtain high efficiency.In recent years, polymer solar cells have emerged as a low cost alternative to silicon solar cells.
However, fullerenes are unstable under illumination, and form large crystals at high temperatures. Researchers led by Professor Jianhui Hou at the Chinese Academy of Sciences (CAS) developed a unique combination of a polymer called PBDB-T and a small molecule called ITIC.
With this combination, sun’s energy is converted with an efficiency of 11 per cent, a value that strikes most solar cells with fullerenes, and all without fullerenes.
Researchers have characterised the loss spectroscopy of photovoltage (Voc), a key figure for solar cells, and proposed approaches to further improving the device performance.
“We have demonstrated that it is possible to achieve a high efficiency without using fullerene, and that such solar cells are also highly stable to heat,” said Feng Gao, from Linkoping University in Sweden. “Because solar cells are working under constant solar radiation, good thermal stability is very important,” said Gao.
“The combination of high efficiency and good thermal stability suggest that polymer solar cells, which can be easily manufactured using low-cost roll-to-roll printing technology, now come a step closer to commercialisation,” said Gao. The research was published in the journal Advanced Materials.