Researchers at the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia reported a power conversion efficiency of 17% for organic solar PV (OPV) cells after they used a hole-transporting layer made from flakes of a 2D material, tungsten disulfide (WS2) to help channel charge in flexible photovoltaics.
They claim this efficiency level is the highest for any OPV using 2D material as a hole transporter and among the highest for any OPV. "We were very surprised to reach 17%," said Yuanbao Lin, a Ph.D. student of the team. "We feel this is just the beginning and there is significant room for performance improvement." They found the tungsten disulfide layer having a lower resistance than PEDOT:PSS and is better at gathering holes.
Conducted by the team at KAUST Solar Center, the researchers used ultrasound to tear the flakes off powdered tungsten disulfide suspended in a mixture of water and ethanol and call this sonication method an 'inexpensive' one that's easy to scale up. Flakes can be spread onto an electrode using a simple and widely used spin-coating process, they said.
Thomas Anthopoulos said his team will now explore efficiency level for OPV cells beyond 17% and towards theoretically predicted limits as well as study the stability of these high-efficiency organic solar cells.
Their research work has been published in Advanced Materials scientific journal.