Technology and Operating Principles of Silicon-based Heterojunction Solar Cells (TopShot)
The combination of amorphous/crystalline silicon (a-Si:H/c-Si) heterojunctions (SHJ) and back-contacted back-junction solar cell concepts offers a very high efficiency potential of 24%. Solar cells with a-Si:H/c-Si heterojunctions have proven open circuit voltage values exceeding 740 mV (Mishima et al.). Back-contacted cell architectures allow for the avoidance of contact shading losses. Furthermore optical losses in the front a-Si:H layer and front transparent conductive oxide as present in both-sides-contacted SHJ solar cells can be circumvented.
One objective of the project TopShot is to develop appropriate contact systems including amorphous silicon layers, transparent conductive oxides and/or metal. Furthermore patterning processes for these layers, that are compatible with the high passivation quality of the a-Si/c-Si interface are investigated. These components are tested on small area solar cells in a first step, and subsequently upscaling of the area is addressed.
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