Solar power is one of the world’s most important clean energy sources, and scientists are constantly searching for ways to make solar panels more efficient and affordable.
One of the most promising technologies is the perovskite–silicon tandem solar cell, which combines two different light-absorbing materials to capture more energy from sunlight than traditional silicon panels alone.
Now, researchers from the Karlsruhe Institute of Technology and the University of Valencia have developed a new manufacturing method that could help bring these advanced solar cells closer to large-scale industrial production.
Their findings were published in the journal Nature Energy.
Perovskite–silicon tandem cells work by dividing sunlight into different energy ranges.
The top layer, made from perovskite, absorbs high-energy blue and ultraviolet light, while the silicon layer underneath captures lower-energy red and infrared light.
By sharing the work, the two layers can convert more sunlight into electricity than ordinary silicon solar cells.
Although these tandem cells can achieve very high efficiencies, manufacturing them on a large scale has been difficult. One major problem is how to quickly and evenly coat the silicon surface with an extremely thin layer of perovskite material.
To solve this, the researchers improved a process called close-space sublimation, or CSS. In this method, solid precursor materials are heated until they evaporate. The vapor then travels only a very short distance before landing on the silicon surface, where it reacts to form the perovskite layer.
Unlike many existing methods, the CSS process does not require liquid solvents. This makes the process cleaner and potentially cheaper for industry. It also uses less material and allows some components to be reused.
The researchers said the process was surprisingly fast. The perovskite layer fully formed in only 10 minutes, which is considered a major improvement for vacuum-based manufacturing techniques.
Another important challenge was controlling the “band gap” of the perovskite layer. The band gap determines which parts of sunlight the material absorbs. For tandem solar cells to work efficiently, the top layer must absorb only certain wavelengths while letting others pass through to the silicon underneath.
The team adjusted the chemical composition by mixing two organic compounds containing iodine and bromine. This allowed them to fine-tune the material and achieve the desired band gap of 1.64 electronvolts.
The researchers also tested the process on different types of silicon surfaces, including smooth, nano-textured, and micro-textured designs commonly used in commercial solar cells. Impressively, the same process worked well on all surfaces without major adjustments.
The finished tandem solar cells achieved efficiencies between 23.5% and 24.3%, depending on the surface structure. Just as importantly, the perovskite layers remained smooth and uniform across all designs.
The researchers believe this is an important step toward mass production of next-generation solar panels that are both highly efficient and practical to manufacture.
Source: KSR.
