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Published on : Nov 14, 2018

Researchers have devised a new way of building tandem solar cells that allows a more efficient method of light management. A team of researchers from Helmholtz Zentrum Berlin has recently announced that their monolithic silicon/perovskite heterojunction tandem solar cells has showcased a record-breaking efficiency of 25.5% and that reaching an efficiency of 32.5% is an achievable target with the use of this method.

One of the leading challenges with tandem solar cells made from metal halide perovskite compounds and silicon is that a part of light is reflected and lost for energy conversion purposes. This challenge can be significantly assuaged by using nanostructures, such as microfeatures of the shape of pyramid imprinted onto the surface of silicon. However, this can lead to microscopic roughness on the surface of silicon, which can make the process of depositing thin layers of perovskite challenging.

In the new approach adopted by the research team, silicon layer was separately applied on the back of the cell and the perovskite layer was etched onto the front, smoother side of the silicon. After this, a polymer light management (LM) foil was etched to the device’s front portion. As a result, a high-quality perovskite film was applied on the flat surface.

The researchers have also devised a complex numerical model that can analyze the interaction of light with complex 3D features. The model can easily allow scientists to calculate how various device designs with textures applied across different interfaces impact the efficiency of the final product. Based on this model, the researchers opine that achieving an efficiency of 32.5% may not be an unachievable feat and is, in fact, realistically achievable.