Regulating the Crystallization Behavior of Quasi-2D Dion-Jacobson Tin Perovskites with a Non-linear Organic Spacer

Abstract

Compared with traditional 3D tin perovskites, 2D tin perovskites have received extensive research attention due to their excellent environmental stability and unique charge carrier behaviors. Among them, 2D Dion-Jacobson (DJ) perovskites have been widely studied because of their stronger interlayer interactions and higher structural stability. In this work, quasi-linear 4,4'-ethylenedianiline dihydroiodide (EDANI2) and non-linear 4,4'- methylenedianiline dihydroiodide (MDANI2) were introduced as organic spacers for quasi-2D DJ tin perovskites with n = 10. Density functional theory calculations showed that the non-linear MDAN2+ has a larger dipole moment than the EDAN2+. Compared with EDAN2+, the stronger interaction between the non-linear MDAN2+ and the tin perovskite induces the formation of tin perovskite films with larger grain sizes and flatter morphology, which improves the carrier transport. Meanwhile, the in-situ photoluminescence measurements revealed a rapid nucleation and delayed crystallization growth for the MDAN film. Finally, the quasi-2D DJ solar cells with MDANFA9Sn10I31 achieved a power conversion efficiency (PCE) of 5.62%, which was substaincially higher than that of the EDANFA9Sn10I31 device (4.53%). After being stored in a nitrogen atmosphere for 2000 h, the MDANFA9Sn10I31 device maintained more than 90% of the initial PCE. This work shed light on the structural dependence of organic spacers on the crystallization behaviors of 2D lead-free perovskites.