Fast and low temperature growth of electron transport layers for efficient perovskite solar cells

Abstract

We describe a fast, simple and low temperature electrochemical technique for the preparation of zinc oxide layers on rigid and flexible substrates. The layers, prepared from a zinc nitrate precursor, are of high structural and optical quality. They have been optimized to be applied as efficient electron transport layers in CH₃NH₃PbI₃-sensitized perovskite solar cells (PSCs). We show that an electrodeposition time of only two minutes and a low processing temperature are sufficient to fabricate solar cells with a power conversion efficiency close to 11%, with a high short circuit current and a small J–V curve hysteresis. The key parameters of the cell functioning have been analyzed over a large applied voltage range by the impedance spectroscopy technique. The solar cell characteristic changes with the ZnO layer deposition time are explained by the variation of the recombination and charge transfer resistances.