Comparison between textured SnO2:F and Mo contacts with the p-type layer in p–i–n hydrogenate amorphous silicon solar cells by forward bias impedance analysis

In this paper we compare the performance of the textured SnO2:F and Mo contacts with the p-type layer in p–i–n hydrogenate amorphous silicon (a-Si:H) solar cells. We use standard current–voltage (I–V) electrical characterization methods coupled with forward bias small signal impedance analysis. We show the efficacy of this technique to determine the effective carrier lifetime in photovoltaic cells. We show that such effective lifetimes are indeed directly connected to the respective dark diode saturation currents. We also find that the effective lifetime is constant with the temperature in the 0–70 °C range and it is significantly better for the solar cell with Mo diode contact. This also explains well the higher open circuit voltage Voc found under illumination in the Mo/p–i–n cell compared to the SnO2:F/p–i–n one.

► Two types of p–i–n a-Si:H solar cells were made by STMicroelectronics.
► The cells differ only for the type of front contact.
► We apply an impedance measurement technique to determine the carrier lifetimes.
► We found that the Mo diode has a higher lifetime than the SnO2:F diode.
► This method is an effective tool to evaluate the carrier lifetime of solar cells.