The photovoltaic conversion efficiency of p-i-n amorphous silicon solar cells have been calculated by computer simulation, and the effect of the increase of hole diffusion length $L_p$ on the cell performance was investigated.
In the calculation of space charge distribution in a-Si films, the shifted-U form was assumed for the distribution function of the density of states in the gap.
The computed cell characteristics were compared with the experimentally measured performances, and the theoretical limit efficiency of the p-i-n solar cell was estimated to be 12.3% assuming 0.15 um of $L_p$.
The efficiency can be increased up to 13.3% by adding multiple internal reflections.
