Dark J-V characteristic of p-i-n a-Si:H solar cells

The J-V characteristics of p-i-n solar cells in the dark have been simulated by solving numerically the full set of transport equations. We have analyzed the dependence of dark current on the density of gap states in the intrinsic layer and on the presence of interface states between the p and i layers. The dependence on the thickness of the intrinsic layer has also been investigated and we have found that the agreement with the experimental data is possible only in the presence of interface states. A simplified model which qualitatively explains the results of the complete simulation has been developed. We have also investigated the changes of J-V characteristics with measurement temperature obtaining results in good agreement with the experimental data without introducing any tunneling mechanism.