in the october 21 issue of science, a team of researchers from stanford university and oxford university reported on a new process that incorporates tin and other common elements to create perovskite, which is a photovoltaic crystalline material that is thinner, more flexible and easier to produce than standard silicon crystals.

a perovskite solar cell. (youtube)

the abstract for the report stated:

“we demonstrate four and two-terminal perovskite-perovskite tandem solar cells with ideally matched bandgaps. we develop an infrared absorbing 1.2ev bandgap perovskite, fa_0.75cs_0.25sn_0.5pb_0.5i₃, that can deliver 14.8% efficiency.

“by combining this material with a wider bandgap fa_0.83cs_0.17pb(i_0.5br_0.5)₃ material, we reach monolithic two terminal tandem efficiencies of 17.0% with over 1.65 volts open-circuit voltage. we also make mechanically stacked four terminal tandem cells and obtain 20.3% efficiency.

“crucially, we find that our infrared absorbing perovskite cells exhibit excellent thermal and atmospheric stability, unprecedented for sn-based perovskites. this device architecture and materials set will enable ‘all perovskite’ thin film solar cells to reach the highest efficiencies in the long term at the lowest costs.”

according to a post on the stanford website, the scientists layered two perovskite solar cells in tandem, rather than having one layer of perovskite on top of a silicon crystal. this will be a significantly easier process since silicon rocks need to be heated at a temperature above 1,600°c to form the crystals that are used in solar cells, while perovskite cells can be created in a lab and printed on glass at room temperature.

the discovery was also recognized by the queen elizabeth prize for engineering in its “create the future” blog series.

learn more about the process in the video below: