For years, perovskite solar cells have held the promise of affordable, high-efficiency energy — yet each sunrise and sunset quietly undid that promise, as the daily rhythm of heating and cooling fractured the crystalline lattice from within. Researchers led by Ma have now answered this structural vulnerability with a structural solution: a two-dimensional perovskite scaffold that guides crystal growth with such precision that the material bends under thermal stress without accumulating the damage that once doomed it. Achieving 26.32% efficiency and retaining 89% stability across 40 simulated d