Semiconducting divalent organic spacer-assisted charge transport in lead-free layered perovskites

Abstract

While employing bulky organic semiconductor cations in layered (2D) hybrid halide perovskites can mitigate dielectric and quantum confinement limitations by enabling charge transfer between organic and inorganic layers, applying this strategy to tin-based perovskites is more challenging due to their more compact structure. Herein, we successfully integrate the strongly π-delocalized naphthalene diimide (NDI) cations with diammonium-functionalized alkyl chain lengths of six carbons (NDI-dH) with tin(II) iodide, forming a layered hybrid organic–inorganic perovskite with a type-II nanoheterojunction electronic architecture. Compared to typical Sn-based hybrid layered perovskite films (prepared with phenylethylamine), the herein reported (NDI-dH)SnI₄ hybrid perovskite demonstrates significantly improved photogenerated charge carrier lifetime and a notable out-of-plane electron mobility reaching 0.1 cm² s⁻¹ V⁻¹. Additionally, (NDI-dH)SnI₄ exhibits improved stability in ambient air and nitrogen environments, highlighting its potential for use in air-stable optoelectronic devices.