Photoelectrochemical Characterization of CuInSe2 and Cu(In_(1-x)Ga_x)Se2 Thin Films for Solar Cells

摘要

Photoelectrochemical (PEC) studies of CuInSe2 (CIS) and Cu(In_(1-x)Ga_x)Se2 (CIGS) thin films prepared by electrodeposition and spray coating of nanocrystals were carried out. PEC reductions of methyl viologen (MV) in aqueous solution and ethyl viologen (EV) in acetonitrile were used to evaluate the thin-film performance by measuring the photocurrent. Deposition of a CdS layer on CIS and CIGS films strongly enhanced the photocurrent; for example, a nanocrystal-CIS film showed about 100 times higher photocurrent with a thin CdS layer. Capacitance measurements and Mott-Schottky plots were obtained to find the flat band potential. Incident photon to current conversion efficiencies (IPCE) and absorbed photon to current conversion efficiencies (APCE) obtained from PEC measurements were about 20% and 40—70%, respectively.