Ionic liquid-assisted growth of methylammonium lead iodide spherical nanoparticles by a simple spin-coating method and photovoltaic properties of perovskite solar cells

Abstract

Hybrid organometal halide perovskites such as methylammonium lead iodide (MAPbI₃) are a promising class of cost- and energy-efficient light absorption materials for thin-film photovoltaics. In this work, the preparation and characterization of MAPbI₃ nanoparticles (NPs) on TiO_x/indium tin oxide glass substrates using a simple spin-coating technique have been investigated. The NPs were prepared by spin-coating solutions of MAPbI₃ and the ionic liquid (IL) 1-hexyl-3-methylimidazolium chloride in N,N-dimethylformamide. Analysis of the resulting spin-coated films revealed that uniform spherical MAPbI₃ NPs with an average diameter of 540 nm were homogeneously distributed on the TiO_x substrates. MAPbI₃ films with similar crystallinity were observed irrespective of the inclusion of IL, as evident from the X-ray diffraction patterns of the films. However, addition of IL to the spin-coating solution facilitated the formation of homogenous nucleation sites and prevented rapid crystal formation of MAPbI₃. Therefore, the presence of an IL resulted in uniform thin films with good morphology.