The team tackled perovskite instability by devising a passivation approach that forms a protective 2D layer atop a 3D inorganic perovskite. They synthesized perfluorinated 2D ammonium cations whose strongly electronegative fluorine atoms lower the electron density of the ammonium group, enabling hydrogen bonding between the anchoring ammonium group and lead iodide fragments.
"Passivation makes the perovskite surface chemically inactive, eliminating the defects introduced during production," he noted. For fully inorganic compositions, adhesion is typically poor: "Simply put, 2D layers do not stick to pure inorganic perovskite," he said.
The new chemistry overcame that barrier: "The result was the formation of a stable 2D layer on the surface of the 3D inorganic perovskite. This time, the 2D layers finally adhered, forming robust heterostructures that remain stable even at high temperatures," Dr Rakstys emphasized.
Devices surpassed 21 percent efficiency; mini-modules with active areas more than 300 times larger than standard lab cells reached nearly 20 percent and operated stably for over 950 hours at 85oC under continuous light.
"Although solar cells do not normally reach such high temperatures under real operating conditions, these standardised stability tests are used to assess their long-term durability, and such high stability is practically comparable to the requirements of commercial silicon cells," he added.
The work, involving more than 20 researchers, appears in Nature Energy and underscores that next-generation perovskite technology is advancing toward commercial deployment.
Research Report:Cation interdiffusion control for 2D/3D heterostructure formation and stabilization in inorganic perovskite solar modules
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