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Spray-Pyrolyzed ZnO as Electron Selective Contact for Long-Term Stable Planar CH3NH3PbI3 Perovskite Solar Cells
journal contribution
posted on 2018-07-25, 00:00 authored by Thi Tuyen Ngo, Eva M. Barea, Ramon Tena-Zaera, Iván Mora-SeróElectron selective
contacts (ESCs) play an important role in the performance of perovskite
solar cells (PSCs). ZnO has attracted important attention as a good
material for ESCs because of its matched energy levels with those
of perovskite, its high transmittance in the visible region, and its
high electron mobility. Here we reported the use of ZnO thin layers
prepared by spray pyrolysis as ESC for PSCs. Our ZnO based planar
CH3NH3PbI3 (MAPbI3) devices
not only were stable in a humidity of 35% but also improved the performance
even after more than 1 month of preparation, due to an increase of
charge transfer at the ZnO interface as it has been characterized
by impedance spectroscopy. The formation of ZnO depends on preparation
conditions such as gas flow, zinc acetate solution concentrations,
and substrate temperatures, all of which have an effect on the performance
of stability of MAPbI3 solar cells. Also, the low hysteresis
reported for these samples was discussed in this study. We have also
observed that long-term structural evolution of perovskite film also
depends on the ZnO substrate and its deposition method.