Scientists working with hybrid organic/inorganic perovskite solar cells have discovered that positively charged molecules rotate within a solar cell, and that this movement has the effect of screening excited electrons from recombination, thus increasing the solar cell’s performance.
The team, led by researchers from the University of Virginia, discovered a mechanism whereby positively charged organic molecules (cations) rotate within a perovskite crystal, screening the excited charge carriers. The researchers describe this as the dominant mechanism behind the long carrier lifetime which is responsible for perovskite material’s strong performance as a solar cell.
A combination of neutron and x-ray diffraction, high-performance computing, and opto-electronic measurements was used to observe the effects. The research paper, Origin of long lifetime of band edge charge carriers in organic-inorganic lead iodide perovskites, published in the journal Proceedings of the National Academy of Sciences, notes that the more freedom to rotate available to the cations, the longer the charge carrier lifetime of the material.
This discovery could allow scientists to further even higher efficiency perovskite materials, though as with all developments in this area, the prospect of stability and degradation remains a barrier.