Ionic Liquid Engineering in Perovskite Photovoltaics

Abstract

Over the past decade, perovskite photovoltaics have approached other currently available technologies and proven to be the most prospective type of solar cells. Although the many-sided research in this very active field has generated consistent results with regards to their undisputed consistently increasing power conversion efficiency, it also produced several rather contradictory opinions. Among other important details, debate surrounding their proneness to surface degradation and poor mechanical robustness, as well as the environmental footprint of this materials class remains a moot point. The application of ionic liquids appears as one of the potential remedies to some of these challenges due to their high conductivity, the opportunities for chemical 'tuning' of the structure, and relatively lower environmental footprint. This article provides an overview, classification, and applications of ionic liquids in perovskite solar cells. We summarize the use and role of ionic liquids as versatile additives, solvents, and modifiers in perovskite precursor solution, charge transport layer, as well as for interfacial and stability engineering. Finally, challenges and the future prospects for the design and/or selection of ionic liquids with a specific profile that meets the requirements for next generation highly efficient and stable perovskite solar cells are proposed.

Trap State Passivation for Stabilizing Perovskite Solar Cells via Multifunctional Molecules

“…Ionic liquids (ILs), generally formed with organic cations and organic/inorganic anions, are excellent materials for perovskite passivation. 16 Incorporation of ILs in the perovskite results in high charge carrier mobility and enhanced thermal stability. ILs are also outstanding for the surface passivation of perovskite.…”

Construction of Efficient and Stable FAPbI3 Perovskite Solar Cells through Bifunctional Ionic Liquid‐Assisted Crystallization and Defect Passivation

“…1) The functional groups on imidazole cation can interact with the perovskite component, inhibiting the rapid crystallization process of perovskite, easily promoting the expansion of the lattice, reducing GBs, and improving the film quality. [29,39,43] Cl À is employed to assist grain growth along with preferred orientation of perovskite grains [44][45][46][47][48][49] ; 2) AOMCl still exists in the film after annealing, which can passivate grain boundaries and surface defects and stabilize the α-FAPbI 3 phase. Both imidazole and amide groups contained in AOMCl cations can strongly interact with perovskites; and 3) AOMCl has hydrophobicity groups, which can resist moisture and improve the stability of the PSCs.…”

Solvent Engineering of Ionic Liquids for Stable and Efficient Perovskite Solar Cells

“…The exciting thing is that equally effective applications of ILs occur in the perovskite field, including PSCs, [ 49,50 ] perovskite light‐emitting diodes, [ 51 ] and perovskite photodetectors. [ 51 ] In particular, the additive engineering, [ 52–54 ] interface engineering, [ 55,56 ] and stability engineering [ 57,58 ] of ILs in PSCs have significantly promoted the development of high‐efficiency devices. Unlike organic ferroelectric materials, [ 59 ] 2D materials, [ 60 ] organic semiconductors, [ 61 ] and organic salt [ 62 ] are applied singularly in interfacial or additive engineering for regulating the crystallization of perovskite film, the designability of chemical structures of ILs and the existence of hydrogen bonds as well as electrostatic network provided by cation and anion in ILs have prompted the same attention to ILs in solvent engineering to replace the toxic ones for improving the crystallization process with high quality perovskite film.…”