By combining information on solar cell layer structure and electrical response analyzed by impedance spectroscopy, relevant knowledge is obtained about photogenerated carriers recombination and extraction. The inclusion of a-Si:H buffer layers on the response of bifacial heterojunction silicon solar cells prepared by hot-wire chemical vapor deposition is studied. Impedance analysis indicates that the effect of the buffer layer is twofold: (a) effective minority carrier lifetime is improved by one order of magnitude, confirmed by alternative quasi-steady-state photoconductance, and (b) whole series resistance is increased. Both effects seem to compensate each other so as to get similar efficiency and fill factor.

Peer Reviewed