Molecular Nanolinks Push Perovskite Solar Cells Past 26% With Unprecedented Stability

Perovskite solar cells have long dazzled researchers with their meteoric rise in efficiency, but a stubborn problem has kept them from the factory floor: the interfaces where the light-absorbing perovskite meets its charge-transport layers are fragile, failure-prone, and notoriously inconsistent from device to device. Now a team at The Hong Kong University of Science and Technology reports a way to stitch those interfaces together at the molecular level, achieving a certified power conversion efficiency of 26.67 percent and, more remarkably, a level of operational stability and reproducibility that could finally make perovskite photovoltaics an industrial reality. The work, published in Nature Photonics on 29 September 2026, introduces a strategy the researchers call trans-interface engineering, or TIE, and it rethinks one of the most fundamental assumptions in how these devices are built.

For more than a decade, the standard approach to protecting perovskite solar cells has been planar interface engineering. Researchers deposit thin, flat interlayers of organic molecules, polymers, or inorganic salts between the perovskite absorber and the adjacent charge-transport layer. These interlayers serve two purposes: they chemically passivate dangling bonds and defects at the interface, reducing the recombination of charge carriers, and they act as a kind of glue, interlocking the two layers mechanically. The trouble is that these goals pull in opposite directions. A thicker, denser interlayer bonds the layers together more robustly, but it also adds an insulating barrier that impedes the flow of electrons or holes across the junction. A thinner interlayer lets charges pass freely but offers little mechanical reinforcement. The result has been a persistent trade-off, in which gains in stability come at the cost of efficiency, and vice versa.

The Hong Kong team, led by Yuanyuan Zhou with Pengfei Guo and Wenjian Yu as co-first authors, sidestepped this trade-off by abandoning the flat interlayer altogether. Instead of building a wall between the perovskite and the charge-transport layer, they built bridges through it. Their trans-interface engineering creates vertically aligned, mechanically tough nanolinks that penetrate into both layers simultaneously, anchoring the interface from both sides at once. Because these molecular links are discrete and vertically oriented rather than continuous and planar, they provide mechanical reinforcement without blanketing the interface in insulating material. Charge carriers can still travel across the junction through the unoccupied regions between the nanolinks, while the links themselves hold the two layers together under the thermal and mechanical stresses of operation.

The chemistry behind the nanolinks is a two-step molecular handshake. First, the researchers pre-incorporated two different organic linkers into the device stack: a triple organic linker embedded within the perovskite layer, and a single organic linker distributed in the charge-transport layer. Each linker is designed to integrate into its host layer without disrupting its function. Then came the trigger: the team applied radicals derived from azobisisobutyronitrile, a common free-radical initiator better known in polymer chemistry as AIBN. These cyanoisopropyl radicals initiated polymerization of the two linkers within their respective layers, and, crucially, also bonded the two linker populations to each other vertically at the heterointerfacial contacts. The result is a covalently stitched interface, with polymerized molecular tethers running from the body of the perovskite layer, across the junction, and into the body of the charge-transport layer.

Mechanical testing showed that this stitched interface outperformed other reported interfacial approaches by a wide margin. This matters because mechanical failure, not chemistry alone, has emerged as a leading cause of perovskite device degradation. Metal halide perovskites are soft, brittle ionic crystals, and the repeated thermal cycling, humidity exposure, and mechanical stress of real-world operation cause delamination, cracking, and grain-boundary failure that begin precisely at the heterointerfaces. Previous work from other groups has explored interfacial toughening with self-assembled monolayers, chiral-structured heterointerfaces, and interpenetrating networks, but the trans-interface approach is distinctive in reinforcing the interface from within both layers rather than merely coating it from one side. By suppressing the mechanical failure modes that initiate degradation, the nanolinks address degradation at its root rather than treating its symptoms.

The photovoltaic results are striking. Devices built with the TIE-treated interface achieved power conversion efficiencies of up to 27.04 percent, with an independently certified value of 26.67 percent, placing them among the most efficient perovskite solar cells ever reported. But efficiency records in this field are common; what has been rare is stability delivered reproducibly. Under maximum-power-point tracking at one-sun-intensity illumination, the standard operating condition used to assess how a cell performs while actually generating electricity, 92 percent of the tested devices reached T80 lifetimes of 1,400 hours, meaning they retained at least 80 percent of their initial performance for nearly two months of continuous simulated sunlight. That statistical consistency across a large population of devices is arguably the more important headline, because industrialization depends not on a single champion cell but on thousands of cells that all behave the same way.

The reproducibility stems largely from what the nanolinks prevent. In conventional devices, tiny variations in interface quality from sample to sample translate into wildly different degradation rates, so one cell might last ten times longer than its nominally identical twin. By mechanically reinforcing every interface in the same way, trans-interface engineering narrows that distribution. The team attributes the high reliability chiefly to the suppression of mechanical failure during operation: when the interface cannot delaminate or crack, the chemical degradation pathways that follow mechanical damage never get started. This reframing of stability as a mechanical problem as much as a chemical one echoes a growing consensus in the field, articulated in recent reviews of the mechanical reliability of metal halide perovskites, that fracture and delamination deserve the same attention traditionally reserved for ion migration and moisture attack.

The implications extend well beyond a single efficiency chart. Perovskite solar cells are the leading candidates for next-generation photovoltaics because they can be made cheaply, at low temperatures, on flexible substrates, and in tandem configurations stacked on silicon to break through the efficiency limits of single-junction cells. But investors and module manufacturers have been wary of a technology whose lab champions fade within weeks and whose production batches vary unpredictably. A strategy that simultaneously boosts efficiency, extends lifetime, and tightens the statistical spread of device performance directly addresses the three objections that have kept perovskites out of mass production. The fact that the TIE process relies on well-understood radical polymerization chemistry, compatible with existing solution-processing fabrication, suggests it could be integrated into manufacturing without exotic equipment.

Perhaps the most far-reaching claim in the paper is that trans-interface engineering is not limited to photovoltaics. Multilayered optoelectronic devices of every kind, including organic light-emitting diodes, photodetectors, and perovskite-based transistors, suffer from the same fundamental weakness: dissimilar layers stacked on top of one another form fragile heterointerfaces that fail under stress. A generalizable method for growing vertically aligned molecular links across any such junction, decoupling mechanical reinforcement from charge transport, offers a design principle for the entire field of layered electronics. A US patent has been filed based on the work by Zhou, Guo, and Yu, signaling commercial interest in translating the concept. If the approach survives the transition from laboratory cells to full-size modules and outdoor field testing, the molecular stitching demonstrated here may be remembered as the moment perovskite solar cells stopped being a laboratory marvel and started becoming a product.

Subject of Research: Trans-interface engineering of perovskite solar cell heterointerfaces for efficiency and stability

Article Title: Trans-interface engineering for reliable perovskite solar cells with reproducible stability

Article References: Guo, P., Yu, W., Hao, M., Wang, K., Duan, T., Li, S., & Zhou, Y. (2026). Trans-interface engineering for reliable perovskite solar cells with reproducible stability. Nature Photonics. https://doi.org/10.1038/s41566-026-02007-w

Image Credits: AI Generated

DOI: 10.1038/s41566-026-02007-w

Keywords: perovskite solar cells, trans-interface engineering, nanolinks, power conversion efficiency, operational stability, interface engineering, radical polymerization, mechanical reliability, charge transport, photovoltaics, heterointerfaces, reproducibility