From Metallic Lead Films to Perovskite Solar Cells through Lead Conversion with Polyhalide Solutions

Abstract

Solutions of methylammonium and formamidinium polyhalides (AX1+n , A = MA, FA, X = I, Br) in isopropanol are introduced as novel versatile precursors for the fabrication of APbX3 hybrid perovskite thin films via oxidation of metallic Pb. The polyhalide solution with adjustable reactivity is distributed over a metallic Pb layer followed by iodine vapor postprocessing to tune the morphology and composition of the film using only the elements inherently present in the perovskite. This method is easily reproducible in any materials science laboratory with equipment commonly used for perovskite solar cell fabrication and resulted in power conversion efficiencies of 16.2 and 17.2% for planar solar cells using MAPbI3 and MA0.25FA0.75PbI2.75Br0.25 perovskites, respectively, as a proof of concept. Implementation of metallic lead thin films as the single Pb-containing precursors reduces a number of in-lab handling hazards compared to classical PbI2 powder and solutions and provides a variety of scalable deposition options.

New Methylamine-Iodine-Mediated Solvent-Free Approach of Hybrid Perovskite Synthesis via the Redox Conversion of Metallic Lead Films

“…Thin films of Pb with a target thickness of 62 nm were deposited on FTO substrates by the thermal evaporation of metallic Pb (99.99%) in vacuum at a deposition rate of 0.1 nm/s as described by Belich et al in ref . After the deposition, the samples were transferred into an Ar-filled glovebox.…”

“…Recently, a novel promising strategy has been proposed for the formation of thin perovskite films by the chemical conversion of a predeposited layer of metallic lead − using reactive polyiodide melts (RPMs) acting simultaneously as either an oxidizer or the source of organic cations and iodine. However, these approaches faced the difficulty of RPMs dosing by virtue of their high recrystallizing ability .…”

Methylammonium Polyiodides in Perovskite Photovoltaics: From Fundamentals to Applications

“…Upon evaporation of isopropanol, pure RPM is formed starting to react with the lead film. Using this method high-quality perovskite films were obtained and perovskite solar cells with PCE = 17.8% (reverse scan) were demonstrated (Figures 2d,e) (Belich et al, 2020).…”

“…In particular, Cs 0.05 MA 0.2 FA 0.75 PbI 3 perovskite films and corresponding devices were obtained by RP-MAGIC approach [T m (Cs 0.05 MA 0.2 FA 0.75 I 3 ) = 38 • C] (Turkevych et al, 2019). Mixed compositions [MA 0.5 FA 0.5 PbI 3 , MA 0.25 FA 0.75 PbI 3 , MA 0.25 FA 0.75 PbI 2.75 Br 0.25 , (FAPbI 3 ) 0.83 (MAPbBr 3 ) 0.17 ] were obtained by spin-coating of the RPM solutions onto Pb films (T m of all corresponding polyhalides < 5 • C) (Petrov et al, 2019;Belich et al, 2020). Further optimization of polyhalide compositions as well as their application techniques is therefore a vital scientific task which can further improve the efficiency of the devices obtained using RPM.…”

Molecular and Supramolecular Structures of Triiodides and Polyiodobismuthates of Phenylenediammonium and Its N,N-dimethyl Derivative

“…The desire to create efficient synthetic pathways for production of hybrid perovskites is a strong motivation for finding alternatives to solvent-assisted fabrication methods, which exhibit various drawbacks such as inaccurate coverage of the perovskite layer across the substrate. In contrast, the polyiodide-assisted fabrication method is capable of transforming a layer of metallic lead several tens of nanometers thick into a uniform layer of a hybrid perovskite by applying triiodide of the selected organic and/or inorganic cation [ 3 , 4 ]. Although Pb-based hybrid perovskites retain their advantages for solar power stations located in non-residential areas, the neurotoxicity of lead should be considered extremely seriously when building integrated perovskite PV systems.…”