A team of researchers from the Arizona State University's (ASU) Ira A. Fulton Schools of Engineering and the University of Nebraska-Lincoln announced it achieved a 25.4% efficiency for a tandem solar cell stack of perovskite and silicon. ASU added chemicals to the perovskite precursor solution to improve their former efficiency record.
By spinning the precursor solution on top of a silicon cell, the researchers found the additives increase the grain size of perovskite, leading to an increase in the maximum voltage that the solar cell produces.
This is an improvement over ASU's previous 'world record' of 23.6% efficiency. The team claims they will be bearing 30% tandem efficiency within 2 years. Their research paper was published in a Cell Press Journal, called Joule.
"Based on our previous 23.6% tandem with a voltage of only 1.65 V, we saw a huge opportunity for higher voltage to get higher efficiency," said ASU's Assistant Research Professor Zhengshan 'Jason' Yu. "The 1.80 V open-circuit voltage of the new tandem is the highest demonstrated, making it one of the most efficient perovskite/silicon tandem cells in the world.
Yu, along with ASU's Assistant Professor Zachary Holman, was also part of the ASU research team's work on high-efficiency tandem PV modules as substitute for traditional silicon based module technology (see Making The Case For Tandem Cell Technology).
The team said they are laying the foundation for the commercialization of perovskite/silicon tandem technology and expect its tandem solar cell technology to be on roofs in the next decade. In October 2018, the team won a grant of $2.5 million from the US Department of Energy's SETO to develop characterization tools to ascertain losses in perovskite solar cells and use a new deposition technique to minimize short-circuit current and fill factor losses to improve solar cell efficiency (see $53mn From US DOE To Fund Early Stage Solar Tech).
The ASU researchers believe the perovskite/silicon tandem cell has the potential to transform mainstream silicon technology and bring down the cost of solar power.
In December 2018, Oxford PV achieved 28% power conversion efficiency for a perovskite-silicon tandem solar cell (see 28% Efficiency For Oxford PV Perovskite Cell).