What it is
Researchers find that acidic protons on phosphonic acid interlayers weakly bound to indium tin oxide accelerate iodide oxidation, formamidinium decomposition, and lead reduction in perovskite solar cells, with these reactions worsening at high temperature and under ultraviolet light. By synthesizing a bis(diarylamino)biphenyl-based phosphonic acid that binds indium tin oxide more strongly, they reach an operational lifetime of nearly 3000 hours to 10% efficiency loss (T90) at 85°C under a metal halide lamp that includes ultraviolet light, with maximum power point tracking. Minimodules achieve power conversion efficiencies above 22% over an aperture area greater than 20 square centimeters, holding a T90 lifetime of about 2200 hours under similar testing conditions.
Why it matters
Phosphonic acid interlayers are widely used in perovskite solar cells but destabilize at elevated temperatures, and this work traces that failure to acidic protons on molecules only weakly bonded to the electrode. Strengthening that bond reduces a chemical degradation pathway that limited stability under the combined heat and ultraviolet exposure of the accelerated stability test.
How to read this
Stabilizing the interlayer-to-electrode bond, not only the perovskite itself, is a route to modules that better hold efficiency under sustained heat and light.
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