Strategies To Improve Performance and Stability for Tin-Based Perovskite Solar Cells

Abstract

This Perspective reviews the developments of tin-based perovskite solar cells (PSCs) during the period 2014-2019 based on two organic cations (methylammonium vs formamidinium) and two device architectures (normal vs inverted) with the strategies of using cocations and coadditives. Unlike their lead-based analogues, tin-based PSCs suffer from the problems of Sn2+/Sn4+ oxidation and film formation. The current best cell is based on an inverted planar FASnI(3) device with guanidinium as cocation, SnF2 as additive, and ethyl-enediammonium iodide as coadditive, which attains record efficiency near 10% with great stability. The device stability and performance might be further improved upon introducing bulky organic cations with a suitable coadditive to form a hybrid 2D/3D crystal structure. Considering the theoretical limit on device efficiency for tin-based PSCs to be, similar to 33%, there is much room for further performance improvement if the problems can be resolved according to the approaches discussed in this Perspective.