Computer simulation of the effect of phosphorous doping of the i-layer in a thin-film a-Si:H p–i–n solar cell

The simulation RAUPV2 has been used to model a thin-film a-Si:H p–i–n solar cell, fabricated at the Rand Afrikaans University. For a physically acceptable set of input parameters, the simulated J–V curve agrees very well with the empirical J–V curve, under AM1.5 g illumination. The effect of boron- and phosphorous doping of the i-layer (B- and P-profiling) was studied. It was found that boron doping of the i-layer greatly reduced cell performance. On the other hand, there seemed to be an optimal phosphorous concentration in the i-layer, Popt, for which cell performance, measured in terms of maximum power output, was a maximum. It was observed that as the P concentration in the i-layer was increased towards Popt, the recombination rate in the front of the i-layer decreased, whilst that in the back part of the i-layer increased. The short-circuit current was seen to decrease under P-profiling. It was seen that as a consequence of P-profiling, the drift field in the back part of the i-layer was relatively insensitive to the effect of an applied voltage, for applied voltages up to about 0.55 V.