The Chemistry of the Passivation Mechanism of Perovskite Films with Ionic Liquids

Abstract

Passivation of perovskite films by ionic liquids (ILs) improves the performance (efficiency and stability) of perovskite solar cells (PSCs). However, the role of ILs in the passivation of perovskite films is not fully understood. Here, we report the reactions of commonly used ILs with the components of perovskites. The reaction of ILs with perovskite precursors (PbI2 and methylammonium iodide or formamidinium iodide) in a 1:1:1 molar ratio affords one-dimensional (1D) salts composed of the IL cation interspersed along infinite 1D polymeric [PbI3]− n chains. If the IL is applied in excess, the resulting crystal is composed of six cations surrounding a discrete [Pb3I12]6– cluster. All the isolated salts were unambiguously characterized by single-crystal X-ray diffraction analysis, which also reveals extensive hydrogen-bonding interactions.

Retarding solid-state reactions enable efficient and stable all-inorganic perovskite solar cells and modules

“…The 19 F NMR spectrum a single peak at −79.19 ppm (fig. S13B), which is characteristic of the CF 3 groups in the TFSI − anion ( 48 ). (ii) A four-component reaction between [PPN][TFSI], DMAI, PbI 2 , and CsI was also performed with each component in 1:1:1:1 molar ratio in DMF.…”

How the ionic liquid BMIMBF4 influences the formation and optoelectronic properties of MAPbI3 thin films

“…From our investigations in Section 2.1, we know that the solvent-complex phase begins to form after 15 s, independent of the IL content. For the solvent engineering experiments, we thus varied the AS dripping time point t ASD after the start of the spin coating between 6 s, 12 s, and 15 s. Here t ASD = 6 s allows to investigate the effect of a relatively early AS dripping on the film formation, t ASD = 12 s represents an AS dripping time point that is often used to prepare high efficient perovskite solar cells, 54 and t ASD = 15 s is close to the latest possible addition of the AS prior to solvent complex formation.…”

“…allows to investigate the effect of a relatively early AS dripping on the lm formation, t ASD ¼ 12 s represents an AS dripping time point that is oen used to prepare high efficient perovskite solar cells, 54 and t ASD ¼ 15 s is close to the latest possible addition of the AS prior to solvent complex formation. Fig.…”

Role of Ionic Liquids in Perovskite Solar Cells

“…ILs can react with the perovskite of the top surface to improve the efficiency and stability of PSCs. [ 71 ] Zhang et al employed EMIMBF 4 to modify the top surface of MAPbI 3 . [ 72 ] After annealing at 100 °C for 5 min, the top surface of MAPbI 3 was reconstructed by EMIMBF 4 and formed (EMIM) x MA 1− x Pb[(BF 4 ) x I 1− x ] 3 .…”