UCLA engineers create tandem polymer solar cells that set record for energy-conversion

In a new study, researchers at the UCLA Henry Samueli School of Engineering and Applied Science and UCLA's California Nanosystems Institute (CNSI) report that they have significantly enhanced polymer solar cells' performance by building a device with a new "tandem" structure that combines multiple cells with different absorption bands. By using cells with different absorption bands, tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation; the device had a certified power-conversion efficiency of 8.62 percent and has set a world record. Researchers have demonstrated highly efficient single-layer and tandem polymer solar cells featuring a low-band-gap-conjugated polymer specially designed for the tandem structure. The band gap determines the portion of the solar spectrum a polymer absorbs. This study opens up a new direction for polymer chemists to pursue designs of new materials for tandem polymer solar cells and indicates an important step towards the commercialization of polymer solar cells.