Polysilicon-based tunnel junction Si solar cells with machine learning
for tandem cell applications
Abstract
Tandem solar cells are a key technology to exceed the theoretical
efficiency limit of single-junction cells. One of the most promising
combinations is the silicon-perovskite tandem cells, considering their
potential for high efficiency, large-area fabrication, and low cost.
Whereas most research focuses on improvements in each subcell, another
key challenge relies on the tunnel junction that connects subcells and
affects overall cell characteristics. Here, the first demonstration of
tunnel junctions using a stack of
p+/n+ polysilicon deposited directly
on the passivating tunnel oxide are shown to overcome the drawbacks of
conventional metal oxide-based tunnel junctions including low tunneling
efficiency and sputter damage. Furthermore, using Random Forest
analysis, high implied open circuit voltages over 700 mV in the bottom
cell with the polysilicon tunnel junction are achieved. Their contact
resistivities are as low as 500 mΩ·cm2, suggesting FF
losses of less than 1 %abs for the operating conditions of a tandem
cell.