Researchers from China Jiliang University, Wuhan University, Hangzhou Dianzi University and Hubei Normal University have introduced a bilayer interface engineering strategy that induces a vertically oriented 1D perovskite capping layer on top of a 3D perovskite absorber.
This architecture targets 1D/3D heterostructure perovskite solar cells, which are already known for their exceptional stability but usually suffer from horizontally aligned or disordered 1D phases that hinder carrier transport along the device thickness. By enforcing vertical alignment of the 1D phase, the new design directly improves charge extraction along the preferred transport direction.
In conventional devices, 1D perovskites tend to align parallel to the substrate or in random orientations, creating a bottleneck for longitudinal carrier transport and limiting the overall power conversion efficiency. In contrast, the engineered vertically ordered 1D/3D heterojunction extends carrier lifetime while enabling rapid interlayer charge transfer between the 3D bulk and the 1D capping layer. At the same time, the vertically oriented 1D layer tunes the energy level alignment at the interface and significantly reduces the density of interface trap states, which are a major source of nonradiative recombination.
As a result of these interfacial improvements, the photovoltage deficit is minimized to 350 mV, indicating that the device operates much closer to its theoretical voltage limit. The champion solar cell based on this architecture achieves a maximum power conversion efficiency of 25.9%, with an independently certified efficiency of 26.0%. Under continuous illumination at 85 °C, the 1D/3D devices show excellent durability, retaining 83% of their initial efficiency after 500 hours and 86% after 1200 hours, highlighting the potential of vertically oriented 1D/3D perovskite heterostructures for efficient and stable photovoltaic applications.
