Theoretical studies of the electric field distribution and open-circuit voltage of amorphous silicon-based alloy p-i-n solar cells

Using a computer model based on the solution of the complete set of transport equations we have investigated electric field profiles, carrier distributions and the open-circuit voltage of amorphous silicon-based alloy p-i-n solar cells illuminated through either the p+ or n+ layer. Our results indicate that even with a large difference in the electron and hole band mobilities there is no large difference (<50 mV) in the open-circuit voltage for the two cases. This difference is small because for optimized devices the open-circuit voltage is limited by the recombination current which is relatively insensitive to space charge and Dember effects. We also show that boron doping in the intrinsic layer can drastically alter the electric field profile in these devices, and can increase the open-circuit voltage of p-i-n solar cells with low built-in potentials.