A special thin layer forms on its own and helps solar cells work better by guiding light and charge through the right path.
In the last decade, silicon-based solar cells have improved significantly—from about 15% efficiency in 2015 to nearly 25% by 2025. But reaching higher efficiencies with silicon alone has become increasingly difficult. To break this barrier, a team of Chinese researchers are now using a tandem approach by adding an ultra-thin layer of perovskite on top of silicon.
A recent study introduced a new material design called HTL201, which leverages a self-assembled monolayer (SAM) to create a high-performance interface between the perovskite layer and the solar cell’s transparent conductive oxide.
The breakthrough lies in how the SAM layer is applied. Instead of relying on complex deposition techniques, the team allowed the perovskite molecules to self-assemble naturally into a uniform, dense layer on a transparent oxide surface. This method gives better control over the thickness and orientation of the SAM—factors that have long limited the performance of tandem designs.
HTL201 also reduces photon absorption by the interlayer, allowing more light to pass through and be converted into electricity. In addition, it extracts charge carriers more efficiently, resulting in lower recombination losses.
This structural improvement led to a record-high power conversion efficiency of 34.58% under standard test conditions (1 cm² sample area). The use of perovskite—especially effective at capturing blue and green light—also keeps production costs relatively low.
While the design has not yet been tested outside the lab or under real-world conditions like high temperature and humidity, it demonstrates a strong path forward. Design engineers working on next-generation photovoltaics can explore HTL201 to achieve high efficiency in tandem cells without adding complexity to the manufacturing process.
As more stable and scalable versions are developed, this tandem architecture could make solar power more efficient and more affordable, helping to accelerate the global shift to clean energy.