Equivalent-circuit modeling of microcrystalline silicon pin solar cells prepared over a wide range of absorber-layer compositions

An equivalent-circuit electrical model is used to simulate the photovoltaic properties of mixed-phase thin-film silicon solar cells. Microcrystalline and amorphous phases are represented as separate parallel-connected photodiode equivalent circuits, scaled by assuming that the photodiode area is directly proportional to the volume fraction of each phase. A reasonable correspondence between experiment and simulation is obtained for short-circuit current and open-circuit voltage vs. volume fraction. However the large dip in fill-factor and reduced PV efficiency measured for cells prepared in the low-crystalline region is inadequately reproduced. It is concluded that poor PV performance in this region is not due solely to shunting by more highly-crystalline filaments, which supports the view that the low-crystalline material has transport properties inferior to either microcrystalline or amorphous silicon