Vertically oriented 1D/3D heterojunction for efficient and stable inverted perovskite solar cells.

1D/3D heterostructure perovskite solar cells have attracted considerable attention owing to their exceptional stability. However, conventional 1D perovskites typically align parallel to the substrate or in disordered orientations, hindering longitudinal carrier transport and limiting device efficiency. Here, we introduce a bilayer interface engineering strategy to induce a vertically oriented 1D capping layer on the surface of the 3D perovskite surface. This vertically ordered 1D/3D heterojunction enables extended carrier lifetime with rapid interlayer charge transport. More importantly, the vertically oriented 1D capping layer not only tunes energy level alignment but also significantly reduces interface trap density, thereby minimizing photovoltage deficit to 350 mV. With these merits, the champion device achieves a maximum power conversion efficiency of 25.9% (26.0% certified). Under high-temperature 85 °C and continuous illumination conditions, the 1D/3D devices maintain 83% and 86% of their initial efficiency after 500 and 1200 hours, respectively, demonstrating their excellent practical durability.