Controlled crystal orientation and reduced lattice distortion with a cystamine dihydrochloride spacer for efficient and stable 2D/3D perovskite solar cells†

Abstract

Long-chain organic spacer diamine molecules are pivotal to the development of mixed two-dimensional (2D) and three-dimensional (3D) perovskites, as they integrate the enhanced stability of 2D perovskites with exceptional efficiency of 3D perovskites. Despite their potential, research on incorporating Dion–Jacobson (DJ) 2D components into the two-step fabrication process of 2D/3D perovskites and the effect of organic spacer diamine molecules on crystal orientation and lattice distortion remains insufficient. Herein, a novel organic spacer diamine molecule, cystamine dihydrochloride (CysCl), has been introduced to construct DJ 2D/3D perovskites. The resulting DJ 2D perovskite enables the development of high-quality perovskite films with improved crystal alignment, reduced lattice distortion, alleviated residual stress, and enhanced carrier transport. Consequently, the DJ 2D/3D device achieves an impressive efficiency of 24.54%, outperforming the control 3D perovskite device (22.72%). Notably, the non-encapsulated device retains 86% of its original efficiency after 1400 hours of continuous exposure to AM 1.5G light under ambient air conditions (25 ± 5 °C and 50 ± 5% relative humidity). Additionally, it demonstrates negligible degradation after 675 hours under combined thermal and light stress, meeting the ISOS-L-2 standard.