A new perovskite-organic tandem solar cell developed by researchers at the Chinese Academy of Sciences sets a world-record 28.04% efficiency while maintaining a lightweight and flexible design.
Perovskite-organic tandem solar cells set a new world efficiency record
Can solar cells become even lighter and more flexible without sacrificing efficiency? Researchers at the Chinese Academy of Sciences believe the answer is yes. Their latest study demonstrates major progress in perovskite-organic tandem solar cells, a technology that combines perovskite and organic semiconductor layers to produce lightweight, flexible photovoltaic devices with record-breaking performance.
Led by researcher Ruihan Wu, the team explored one of the most challenging combinations in multi-junction photovoltaics: pairing a perovskite absorber with an organic semiconductor layer. The approach aims to deliver ultra-thin, flexible solar modules while maintaining high conversion efficiency.
To understand the significance of this achievement, it is worth looking at the evolution of this technology.
Why combine perovskites and organic materials?
Perovskites represent one of the most promising materials in next-generation photovoltaics. While single-junction perovskite solar cells have yet to achieve widespread commercial deployment, research has increasingly shifted towards tandem architectures.
Today, scientists are combining perovskites with crystalline silicon, CIGS and even other perovskites. One of the biggest challenges across these technologies is improving resistance to environmental stress such as oxygen, humidity and thermal cycling.
Organic photovoltaics face similar limitations. They are highly sensitive to oxygen, heat and ultraviolet radiation, and generally offer lower efficiencies than inorganic semiconductors. Combining these two material families therefore presents a significant scientific challenge.
Even so, research has progressed steadily. The latest Best Research-Cell Efficiency Chart published by the US National Renewable Energy Laboratory (NREL) previously listed a conversion efficiency of 23.4%, achieved in 2022 by the National University of Singapore (NUS) and the Solar Energy Research Institute of Singapore (SERIS).
A new world record: 28.04% efficiency
Ruihan Wu and colleagues have now surpassed that milestone by establishing a new world record for perovskite-organic tandem solar cells, achieving a certified 28.04% power conversion efficiency.
The device consists of a wide-bandgap upper subcell made from mixed-halide, bromine-rich perovskite, designed to absorb high-energy visible light in the blue and green spectrum. This is paired with a lower organic subcell that captures lower-energy red and near-infrared light.
The two materials complement one another. The upper perovskite layer absorbs ultraviolet radiation that could otherwise damage the organic layer, while the organic layer 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.
This type of lightweight, flexible photovoltaic technology could also attract growing interest in regions such as Africa, where adaptable solar solutions are increasingly being explored for diverse applications.
The new TDB additive solves a key manufacturing challenge
Manufacturing these hybrid solar cells remains one of the biggest obstacles.
During precursor film formation, bromine tends to crystallise much faster than iodine, producing a non-uniform composition. Once exposed to sunlight, iodine and bromine ions can separate, creating defects that trap electrical charges and reduce device performance.
To overcome this issue, Meng Lei’s team developed a smart, photo-transformable molecular additive known as TDB.
TDB acts as a two-stage stabiliser. During manufacturing, it controls crystallisation dynamics and promotes a uniform distribution of halide elements as the film forms.
Once the solar cell is exposed to sunlight, the TDB molecules undergo a light-triggered transformation at the microscopic boundaries of the material. The transformed molecules bond much more strongly to the perovskite grain boundaries, sealing iodine-related defects, preventing ion migration and reducing charge trapping.
This innovation enabled the researchers to significantly improve both efficiency and operational stability, pushing perovskite-organic tandem solar cells to a new global performance benchmark while preserving their lightweight and flexible characteristics.
