Photocurrent Collection Mechanism and Role of Carrier Distribution in p-i-n Quantum Well Solar Cells

We investigate the role of carrier distribution inside the i-region in the photocurrent collection mechanism of p-i-n quantum well solar cells. The device simulation indicates that the increment of Shockley-Read-Hall recombination after illumination strongly depends on the type of photocarriers and i-region majority carriers. As a result, a solar cell with n-type background doping results in efficient collection of photogenerated electrons from quantum wells even at low field, and this has been confirmed with the results of time-of-flight measurement. Based on this finding, we demonstrate a model for estimating carrier collection efficiency which includes the effect of carrier distribution.