Perovskite and silicon are proving to be a formidable duo in the world of solar cells, and now they’ve hit a new record efficiency. A team at Helmholtz Zentrum Berlin (HZB) have developed solar cells with an efficiency of over 32%.
Silicon has long been the industry standard for solar cells, thanks to its efficiency, durability and cost, but current devices are approaching the theoretical maximum limit of efficiency. Perovskite, meanwhile, is a young upstart that’s quickly risen through the ranks and threatens to steal the crown.
But the best outcome seems to be when these two materials put aside their rivalry and team up. Perovskite/silicon tandem solar cells are more efficient than either material alone, thanks to their ability to harvest different parts of the solar spectrum – perovskite taps into blue light better, while silicon focuses more on red and infrared wavelengths.
The new HZB device is made up of a top cell made of several thin layers of perovskite, and a bottom cell that does the same with silicon. Having a series of layers allows the different colors of light to filter down to the lower levels, and minimizes electrical losses. The team also designed a new interface between the active area and the electrodes, which helped boost the overall efficiency of the cell.
The end result is a perovskite/silicon tandem solar cell that boasts an efficiency of 32.5%. This new record, which has been independently verified, is currently the highest of any emerging photovoltaic technology according to a chart kept and regularly updated by the National Renewable Energy Lab (NREL). It's a decent step up from the previous record-holder of 31.25%, achieved just a few months ago, while a year before that it was just shy of 30%. The team claims this latest advance pushes the technology into an important new realm.
“At 32.5%, the solar cell efficiency of the HZB tandems is now in ranges previously only achieved by expensive III/V semiconductors,” said Professor Bernd Rech, scientific director of HZB. “The NREL graph clearly shows how spectacular the last two increases from EPFL and HZB really are.”
Source: Helmholtz Zentrum Berlin
