High-Efficiency Silicon Cell Fabrication and Analysis

The physical efficiency limit of silicon solar cells is 29%. Our research goal is to bring technology as close as possible to this physical limit. A wide variety of concepts are therefore being researched to minimize loss mechanisms to the greatest possible extent. The key aspects here include reducing surface recombination in silicon, lowering recombination losses at metal contacts and maximizing light trapping in silicon (e.g. by using diffraction gratings on the rear side of solar cells).

The purpose of this work is not only to achieve the highest efficiencies, however, but also to develop future technologies. Alongside classic processes such as diffusion and oxidization, newer technologies are also the subject of research. Examples include ALD (atomic layer deposition) for the deposition of ultra-thin passivation layers (e.g. Al₂O₃), ion implantation and PECVD (plasma-enhanced chemical vapor deposition) for depositing amorphous or microcrystalline silicon layers.

New developments and concepts for increasing efficiency and reducing costs sometimes introduce novel, complex processing steps. Such developments therefore demand a high degree of understanding for the relevant physical processes. In addition to comprehensive characterization and analysis tools we employ multidimensional numerical simulations, allowing us to deepen this understanding further. Numerical modeling, both of the manufacturing process and the finished solar cell, is a key enabler in reducing time to market, as it allows major cuts to be made in the number of experiments necessary.
Alongside extensive technological resources, we are therefore able to draw on in-depth characterization methods to manufacture high-efficiency solar cells.