Crystallization dynamics control in perovskite films using alkylamines as additives in a 2-methoxyethanol-based anti-solvent free process

Abstract

We found that the trace amount of alkylamine ligands added to perovskite solutions can act as a nucleation promoter in an anti-solvent free process. We studied the effects of adding alkylamines with different alkyl chain lengths on perovskite film formation using a 2-methoxyethanol single solvent system without adding a Lewis base solvent. Compared to a porous film prepared without additives, the film with oleylamine (OAm) containing an 18-carbon alkyl chain exhibited a smoother surface and denser interior. At optimal conditions, the perovskite solar cell with the OAm-based film exhibited an enhanced device performance of 21.01% compared to that of the pristine film (11.65%). To investigate how alkylamines support the formation of the uniform perovskite film without the assistance of a Lewis base solvent or anti-solvent process, we employed in situ grazing incidence wide-angle X-ray scattering during spin-coating. As a result, we discovered that adding OAm with longer alkyl chains leaded to more nucleation in less time promoting the formation of the dense film. Furthermore, we confirmed that the effect of OAm addition was similar in other solvent systems. Based on the results, we propose a new pathway utilizing alkylamines to control crystallization dynamics in the anti-solvent free process.