An examination of the `tunnel junctions´ in triple junction a-Si:H based solar cells: modeling and effects on performance

The first-principles computer model AMPS is used to model multijunction solar cell performance. The specific cell modeled uses two a-Si:H absorber layers and an a-SiGe:H absorber layer with all a-SiC:H p ⁺ layers and all a-Si:H n⁺ layers, the modeling shows the contacts in these cells depend critically on recombination in x-layers which may be independently present or, in a well-designed cell, purposefully present. These x-layers must be supplied with carriers. This process may be optimized by appropriate bandgap grading. The modeling shows that multijunction contact layers-unless fully optimized-are not simply resistor-like or diode-like in their behavior