Universal 3D/2D Surface Heterojunction‐Based Piperidine Derivatives for Efficient Inverted Perovskite Solar Cells

) of 1.194 V. This strategy demonstrates broad applicability, as flexible devices reached a PCE of 24.26%, and wide-bandgap (1.68 eV) systems achieved 22.72%. Notably, the 3D/2D heterojunction exhibits exceptional long-term stability, maintaining 99% of its initial PCE after 1730 h under ISOS-L-1 protocols at 25 °C, and displaying only 20% PCE degradation after 423 h of maximum power point (MPP) tracking under 85 °C.