Partial Replacement of Dimethylformamide with Less Toxic Solvents in the Fabrication Process of Mixed-Halide Perovskite Films

Abstract

The technology of perovskite solar cells (PSC) is getting close to breaching the consumer market. Yet, one of the current challenges is to reduce the toxicity during their fabrication by reducing the use of the toxic solvents involved in the perovskite fabrication process. A good solubilization of lead halides used in hybrid perovskite preparation is required, and it is only possible with polar solvents. A mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is the most popular solvent combination for a perovskite precursor solution. DMF is necessary to ensure a good dissolution of lead iodide, but it is also the most toxic solvent. In this paper, we study the replacement of the dimethylformamide with presumably less toxic alternatives, such as N-methyl-2-Pyrrolidone (NMP) and ethyl acetate (EA), for the preparation of the K0.1FA0.7MA0.2PbI2.8Cl0.2 (KFAMA) hybrid perovskite. The perovskite thin films were investigated by various characterization techniques: X-ray diffraction, atomic force microscopy, scanning electron microscopy, and UV–vis spectroscopy, while the photovoltaic parameters were determined by measuring the IV curves of the corresponding solar cells. The present study shows that by keeping the same deposition parameters as when only DMF solvent is used, the partial solvent substitution with NMP and EA gives promising results for reducing the toxicity of the fabrication process of KFAMA-based PSCs. Thus, with no specific optimization of the deposition process, and for the maximum possible partial substitution of DMF with NMP and EA solvents, the loss in the power conversion efficiency (PCE) value is only 35% and 18%, respectively, associated with the more structural defects promoted by NMP and EA.

Toxicity of Perovskite Solar Cells

“…These results demonstrated the potential of E "green solvent" in the fabrication of high-performance and stable PVSCs. [88]. (c) An all green solvent system with only two green solvents, water and 2-propanol (IPA), to fabricate the CsPbBr 3 , where water serves to dissolve precursors of Pb(NO 3 ) 2 and CsBr, and IPA serves to dissolve phenethylammonium Bromide (PEABr).…”

“…In another study, Stancu investigated the partial replacement of DMF with less toxic N-methyl-2-Pyrrolidone (NMP) and EA [88]. The PV characteristics of the devices obtained with different solvents are shown in Figure 8b.…”

Optimising the electrochemical reduction of CO2 to oxalic acid in propylene carbonate

“…However, dimethylformamide is toxic and its use will soon be severely restricted in many countries, 34 with N -methyl-2-pyrrolidone/ethyl acetate mixtures 35 and propylene carbonate having been proposed as lower-toxicity replacements. 36 In this context, it is noteworthy that by far the highest current densities and rates of formation of oxalic acid to date by CO 2 electroreduction were reported by Boor et al 30 (Table 1, entry 13) in a (CH 3 ) 4 NCl/propylene carbonate solvent system at a lead cathode.…”