Metastability study and optimization of polymorphous silicon solar cells: The state-of-the-art

Optimization of polymorphous silicon solar cells is carried out through a combination of experiments and modelling of the device characteristics. The improved transport properties of polymorphous silicon films show up in the higher stability of the cells, while the more reactive plasma conditions used in pm-Si:H deposition as compared to a-Si:H result in a deterioration of the TCO/p/i layers (interfaces). This is clearly detected from the modelling results and supported by experiments in which the TCO substrate is protected against the hydrogen rich plasma used in pm-Si:H deposition. Thus the efficiency limiting factors of pm-Si:H cells are clearly presented, their higher stability demonstrated and guidelines to further improve their efficiency established.