Effect of Tunnel Recombination Junction on Crossover Between the Dark and Illuminated Current–Voltage Curves of Tandem Solar Cells

The tunnel recombination junction (TRJ) quality of an amorphous silicon (a-Si)-based tandem junction solar cell can have a significant impact on its performance, where crossover between the dark and illuminated current–voltage curves of a tandem cell indicates a TRJ with poor quality. Therefore, it is critical to be able to understand the TRJ characteristics in order to optimize the tandem solar cell performance. A simulation approach requiring a few data points was used to quantify the TRJ quality. The uniform field collection model was modified to account for parasitic losses due to the TRJ, which are a voltage drop across the TRJ and a series resistance due to the TRJ. Simulation results using the TRJ model are in good agreement with experimental data. The TRJ model can be a useful tool to aid in the optimization of a-Si-based multijunction solar cells.