Perovskite/perovskite/silicon triple-junction solar cells have taken another significant step toward the efficiency levels needed to transform next-generation photovoltaics. In a study published in Nature, researchers report a device architecture that combines molecular defect passivation in a wide-bandgap perovskite with carefully engineered optical interference control. The resulting solar cells achieved certified steady-state power conversion efficiencies of 32.22% over an aperture area of 1.046 square centimetres and 26.97% over a much larger 15.62-square-centimetre area. The results address two of the most persistent obstacles facing complex tandem photovoltaics: voltage losses caused by imperfections in perovskite materials and current losses caused by light being inefficiently distributed through the multilayer structure.
Triple-junction solar cells are designed to capture a broader portion of sunlight than conventional single-junction devices. Instead of relying on one absorber to convert all usable photons, the architecture stacks three sub-cells with different bandgaps. A wide-bandgap perovskite at the top absorbs higher-energy visible photons, a second perovskite layer converts a different part of the solar spectrum, and a crystalline silicon bottom cell captures lower-energy near-infrared light. When these sub-cells are connected in series, the voltages generated by each junction add together. However, the current is limited by the sub-cell producing the lowest current, making both electronic quality and optical design critical to overall performance.
The researchers focused first on the top wide-bandgap perovskite, where defects at or near the surface can severely reduce the voltage of a solar cell. These defects create electronic states inside the material’s bandgap. Photogenerated electrons and holes can become trapped at these states and recombine before they contribute to an external current. This process, known as non-radiative recombination, releases energy as heat rather than light and lowers the quasi-Fermi-level splitting, a key measure of the maximum voltage that a photovoltaic absorber can generate under illumination.
To suppress these losses, the team introduced a passivating molecule known as 4F-POEABr. The molecule contains an ammonium group that can interact with the perovskite surface and an electron-deficient molecular structure designed to influence the local electronic environment. According to the researchers, these features provide two complementary forms of protection. Chemical passivation reduces the activity of defect sites, while field-effect passivation changes the distribution of electrical charge near the surface, making it more difficult for electrons and holes to encounter one another and recombine.
The effect was reflected in the electronic quality of the treated wide-bandgap perovskite. The material reached a quasi-Fermi-level splitting of 1.53 electron volts, indicating a substantial reduction in voltage loss under illumination. When incorporated into a sub-cell, it produced an open-circuit voltage of 1.413 volts. Open-circuit voltage is measured when no current is drawn from the device, and in high-efficiency solar cells it provides a direct indication of how effectively the absorber preserves photogenerated charge. Achieving a high voltage in a wide-bandgap perovskite is especially important because the top cell must generate substantial voltage while transmitting suitable light to the sub-cells beneath it.
The study also tackles a less visible but equally important problem: how light travels through the stack. In a triple-junction device, photons pass through multiple transparent electrodes, transport layers, perovskite absorbers and interconnection layers before reaching the silicon cell. At every boundary, light can be reflected, transmitted or absorbed. Because the thicknesses and refractive indices of these layers determine how waves interfere with one another, even nanometre-scale changes in a layer can alter the amount of light reaching a particular sub-cell.
The researchers used systematic interference management to increase the current generated by the middle perovskite sub-cell, which limited the current of the series-connected device. Their approach involved tailoring a bilayer made from tin oxide and indium zinc oxide. These transparent conducting and electron-transport components were selected and arranged to modify the optical field inside the stack. By controlling reflection and transmission at the interfaces, the redesigned structure delivered an additional 0.5 milliamperes per square centimetre from the current-limiting middle junction. In a triple-junction device, such a gain can be decisive because excess current from one sub-cell cannot compensate for a shortage in another when all junctions operate in series.
The reported efficiencies show the importance of combining chemical and optical engineering rather than treating them as separate challenges. A device can have excellent material quality yet lose performance if its layers prevent sunlight from reaching the correct absorber. Conversely, sophisticated light management cannot recover voltage lost through severe non-radiative recombination. In the new architecture, molecular passivation improves the voltage contribution of the wide-bandgap top cell, while the tin oxide/indium zinc oxide structure improves current balance through the stack. The two strategies reinforce one another, allowing more of the incident solar energy to be converted into electrical power.
The researchers further report negligible hysteresis, meaning that the measured efficiency showed little dependence on whether the voltage was scanned upward or downward. This behavior is important because hysteresis can make photovoltaic performance difficult to evaluate and may signal charge accumulation or unstable ionic movement within perovskite layers. The devices also incorporated robust interconnection layers and engineered interfaces between the perovskite components. These design elements were intended to improve operational stability and reduce variation from one device to another, two requirements that become increasingly demanding as laboratory-scale cells expand toward commercial dimensions.
The larger-area result is particularly notable because performance often declines when devices grow. Defects, non-uniform coating, resistance in transparent electrodes and alignment errors can all become more consequential over a wider surface. The certified 26.97% steady-state efficiency measured across 15.62 square centimetres therefore suggests that the approach is not limited to a small demonstration area. Although further work will be required to establish long-term outdoor durability, manufacturing compatibility and large-module performance, the study presents a clear roadmap for improving sophisticated tandem architectures: protect the perovskite interfaces, control the electrical environment at defect-rich surfaces and design every transparent layer with both photons and charges in mind. Together, these advances move perovskite/perovskite/silicon triple-junction solar cells closer to the high efficiencies promised by multi-junction photovoltaics.
Subject of Research: Perovskite/perovskite/silicon triple-junction solar cells, molecular defect passivation and optical interference management.
Article Title: Defect passivation and optical management of triple-junction solar cells
Article References: Xu, Y., Wang, Z., Deng, C. et al. Defect passivation and optical management of triple-junction solar cells. Nature (2026). https://doi.org/10.1038/s41586-026-11010-8
Image Credits: AI Generated
DOI: 10.1038/s41586-026-11010-8
Keywords: Perovskite solar cells, triple-junction photovoltaics, silicon solar cells, defect passivation, 4F-POEABr, wide-bandgap perovskites, non-radiative recombination, optical management, interference engineering, solar-cell efficiency.
Tags: advanced device architecture for solar energy conversiondefect passivation in perovskite solar materialshigh-efficiency multi-junction solar deviceslight management techniques in multilayer solar cellsnext-generation photovoltaicoptical interference management in photovoltaicsperovskite silicon tandem solar cellsscalable large-area triple-junction solar modulessolar cell voltage and current loss mitigationtandem solar cell efficiency breakthroughstriple-junction solar cell efficiency improvementswide-bandgap perovskite layer optimization
