Abstract
We report on planar heterojunction perovskite solar cells employing a metal chalcogenide (CdS) electron transport layer with power conversion efficiency up to 10.8%. The CdS layer was deposited via solution-process chemical bath deposition at low-temperature (60 degrees C). Pinhole-free and uniform thin films were obtained with good structural, optical and morphological properties. An optimal layer thickness of 60 nm yielded an improved open-circuit voltage and fill factor compared to the standard TiO2-based solar cells. Devices showed a higher reproducibility of the results compared to TiO2-based ones. We also tested the effect of annealing temperature on the CdS film and the effect of CdCl2 treatment followed by high temperature annealing (410 degrees C) that is expected to passivate the surface, thus eliminating eventual trap-states inducing recombination. (C) 2017 Published by Elsevier B.V.