Researchers at UNIST (Ulsan National Institute of Science and Technology) have made a significant leap in solar technology by developing a new thin-film material that dramatically enhances both the efficiency and durability of tandem solar cells.
This breakthrough, led by Professor BongSoo Kim from the Department of Chemistry, alongside Professors Jin Young Kim and Dong Suk Kim from the Graduate School of Carbon Neutrality, is set to transform the future of clean energy.
The team’s research has been published in the scientific journal Advanced Energy Materials.
Tandem solar cells are cutting-edge photovoltaic devices that stack two different types of solar cells on top of each other.
This unique structure allows them to capture a broader range of sunlight, boosting the amount of electricity generated.
Among the various types of tandem cells, those made from a combination of perovskite and organic materials are especially promising. They are thin, flexible, and could one day power everything from wearable devices to solar panels built directly into buildings.
The UNIST team’s breakthrough came with the development of a special thin-film material called a multi-functional hole-selective layer (mHSL). This layer acts as a bridge between the sunlight-absorbing perovskite and the organic components of the tandem solar cell, allowing electric charges to move more efficiently.
By blending two self-assembled molecules—36ICzC4PA and 36MeOCzC4PA—the researchers created a powerful hole-transport layer (HTL) that significantly improves the solar cell’s performance.
Their design achieved a record-breaking open-circuit voltage (VOC) of 2.216 volts and a power conversion efficiency (PCE) of 24.73%. These figures are among the highest ever recorded for this type of solar cell, marking a substantial step forward in solar energy technology.
But the innovation doesn’t stop at efficiency. The new material also makes the solar cells more durable. In tests, the cells maintained over 80% of their initial efficiency even after long exposure to high temperatures of 65°C and continuous sunlight.
This is crucial for practical applications, where solar panels are exposed to harsh weather and constant sunlight for years.
The secret to this durability lies in the strong chemical bonds formed between the self-assembled molecules and the metal ions in the perovskite layer. These bonds stabilize the crystal structure of the solar cells, reducing defects that would normally disrupt the flow of electricity.
The self-assembly property of the molecules also helps create a smooth, ultra-thin coating over large surfaces, simplifying the manufacturing process.
This makes it easier to produce the solar cells on a large scale, paving the way for wider commercial use. Flexible and lightweight, these solar panels could be installed on everything from curved surfaces to portable electronics, expanding the possibilities for solar energy.
Professor Kim expressed his excitement over the findings, stating, “By developing a self-assembled hole transport layer that improves charge extraction, interface stability, and structural durability, we have made a significant leap forward in enhancing the performance of tandem solar cells.
This development brings us closer to realizing thin, flexible, and high-efficiency next-generation solar panels for practical applications.”
With this innovation, the dream of high-efficiency, flexible solar panels that can be easily integrated into everyday life is closer than ever, bringing the world one step forward in the quest for sustainable energy.
