Chinese researchers have developed a new generation of perovskite-organic tandem solar cells, achieving a record 28.04% efficiency while combining lightweight, flexible materials with improved stability.
Perovskite-organic tandem solar cells reach 28.04% efficiency with a breakthrough hybrid architecture
Can solar cells become even lighter and more flexible without sacrificing efficiency? Researchers from the Chinese Academy of Sciences believe the answer is yes. Their latest study on perovskite-organic tandem solar cells has delivered a new world record in power conversion efficiency while addressing one of the technology’s biggest challenges, long-term material stability.
Led by researcher Ruihan Wu, the team pursued an ambitious tandem photovoltaic architecture by combining a perovskite absorber with an organic photovoltaic layer. The approach aims to deliver ultra-thin, lightweight and flexible solar modules capable of maintaining high conversion efficiencies.
The challenge of combining perovskites and organic materials
Perovskites represent one of the most promising material classes in next-generation photovoltaics. Although single-junction perovskite solar cells have yet to achieve large-scale commercial deployment, research is increasingly focused on tandem configurations.
Double and triple-junction solar cells have become a major research priority, with perovskites being paired with silicon, CIGS and even other perovskite absorbers. Across these approaches, one of the main obstacles remains the material’s sensitivity to environmental stressors such as oxygen, humidity and thermal cycling.
Organic photovoltaics face similar limitations. They are particularly vulnerable to oxygen, heat and ultraviolet radiation, while generally delivering lower efficiencies than inorganic semiconductors. Combining these two material families into a single tandem device therefore presents a significant scientific challenge.
Even so, the technology has already demonstrated promising results. According to the latest Best Research-Cell Efficiency Chart published by the U.S. National Renewable Energy Laboratory (NREL), the previous benchmark for perovskite-organic tandem solar cells was a 23.4% conversion efficiency achieved in 2022 by the National University of Singapore (NUS) and the Solar Energy Research Institute of Singapore (SERIS).
A new world record of 28.04% for perovskite-organic tandem solar cells
Ruihan Wu and colleagues have now raised the performance ceiling by establishing a new world record for perovskite-organic tandem solar cells, reaching a certified power conversion efficiency of 28.04%.
The device features a wide-bandgap mixed-halide perovskite top sub-cell with a high bromine content, designed to absorb high-energy visible light in the blue and green spectrum. It is paired with an organic bottom sub-cell that captures lower-energy red and near-infrared wavelengths.
The two layers complement each other. The perovskite top cell absorbs ultraviolet radiation that could otherwise degrade the organic layer, while the organic sub-cell provides water resistance that helps protect the perovskite material.
“This design allows scientists to ‘tune’ the material, essentially adjusting the specific colours of light that it absorbs,” said Meng Lei, professor at the Institute of Chemistry of the Chinese Academy of Sciences and one of the study’s authors.
TDB additive improves stability and manufacturing
A major manufacturing challenge for these hybrid solar cells arises during the formation of the precursor film. Bromine tends to crystallise faster than iodine, creating an uneven distribution of halides within the material.
When exposed to sunlight, this non-uniform composition causes iodine and bromine ions to separate, creating charge-trapping defects that reduce device performance.
To overcome this limitation, Meng Lei’s team developed a new photo-transformable molecular additive known as TDB.
During manufacturing, TDB regulates crystallisation dynamics and promotes a more uniform distribution of halide elements throughout the film. Once the solar cell is exposed to sunlight, the additive undergoes a light-induced molecular transformation at the material’s microscopic grain boundaries.
The transformed molecule bonds more strongly with the edges of the perovskite grains, sealing iodine-related defects, suppressing ion migration and preventing charge carriers from becoming trapped. The result is a more stable and efficient perovskite-organic tandem solar cell, offering improved performance while preserving the lightweight and flexible characteristics that make this photovoltaic architecture particularly attractive for future applications.
