PbS colloidal quantum dot/ZnO-based bulk-heterojunction solar cells with high stability under continuous light soaking

PbS colloidal quantum dot (CQD)-based depleted bulk-heterojunction solar cells were constructed, using the 1.2 mu m thick nanowire array infiltrated with PbS QDs bearing Br ligands. The long-term stability tests were performed on the solar cells without encapsulation in air under continuous light soaking using a Xe lamp with an AM1.5G filter (100 mW cm(-2)). Time course of solar cell performances during the tests showed two time periods with distinct behavior, that is, the initial transient time period and the relatively stable region following it. The power conversion efficiency was found to keep approximately 90% of the initial value at the end of the 3000 h light soaking test. The stability tests suggest that the PbS surface modification or passivation reactions play an important role in achieving such a high stability, and demonstrate that PbS CQD/ZnO nanowire array-based depleted bulk-heterojunction solar cells are highly stable. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim