Lead-free low-dimensional tin halide perovskites with functional organic spacers: breaking the charge-transport bottleneck†
Low-dimensional organic–inorganic halide perovskites (OIHPs) have received intense interest largely due to their remarkable stability compared to their 3D counterparts for potential optoelectronic and photovoltaic (PV) applications. However, 2D OIHPs encounter a ‘bottleneck’ of ultra-low conductivity between the inorganic sheets, owing to the intrinsic quantum and dielectric confinements, which usually results in unsatisfactory device performance. Herein, we predict and design a new family of 2D OIHPs to break the charge-transport ‘bottleneck’. The newly designed 2D OIHPs consist of π-conjugated organic species as the spacers. As such, we find that the electronic structures exhibit type-II band alignment (staggered bandgap). Such a band-structure feature by design, if confirmed in the laboratory, re-enforces a materials design strategy for enhancing optoelectronic or PV device performance with 2D OIHPs.