Solar power is not only the fastest growing energy technology in recent history but also one of the cheapest energy sources and the most impactful in terms of reducing greenhouse gas emissions.
A Rice University study featured on the cover of today’s issue of Science describes a way to synthesize formamidinium lead iodide (FAPbI3) ⎯ the type of crystal currently used to make the highest-efficiency perovskite solar cells ⎯ into ultrastable, high-quality photovoltaic films. The overall efficiency of the resulting FAPbI3 solar cells decreased by less than 3% over more than 1,000 hours of operation at temperatures of 85 degrees Celsius (185 Fahrenheit).
“Right now, we think that this is state of the art in terms of stability,” said Rice engineer Aditya Mohite, whose lab has achieved progressive improvements in the perovskites’ durability and performance over the past several years. “Perovskite solar cells have the potential to revolutionize energy production, but achieving long-duration stability has been a significant challenge.”
With this most recent breakthrough, Mohite and collaborators have reached a critical milestone toward making perovskite photovoltaics market-ready. The key was “seasoning” the FAPbI3 precursor solution with a sprinkling of specially designed two-dimensional (2D) perovskites. These served as a template guiding the growth of the bulk/3D perovskite, providing added compression and stability to the crystal lattice structure.
“Perovskite crystals get broken in two ways: chemically ⎯ destroying the molecules that make up the crystal ⎯ and structurally ⎯ reordering the molecules to form a different crystal,” said Isaac Metcalf, a Rice materials science and nanoengineering graduate student and a lead author on the study. “Of the various crystals that we use in solar cells, the most chemically stable are also the least structurally stable and vice versa. FAPbI3 is on the structurally unstable end of that spectrum.”
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