Recent progress in low dimensional (quasi-2D) and mixed dimensional (2D/3D) tin-based perovskite solar cells

Low dimensional (quasi-2D) and mixed dimensional (2D/3D) halide perovskites have emerged in the field of perovskite solar cells. They are more stable than their 3D homologs. However, most of the high efficiency perovskite solar cells contain lead, which is toxic; this toxicity impedes the deployment of this technology through mass production and commercialization. Much effort has been made to reduce the toxicity in perovskite solar cells, which is conducive to the development of environmentally friendly halide perovskite solar cells. Moreover, Sn is currently the most promising element to replace lead and develop lead free perovskite solar cells. Indeed, the high sensitivity of Sn 2+ cations towards moisture and oxygen was a huge challenge for preparing stable solar cells. However, this issue has been solved by incorporating organic ammonium cations with different sizes and functional groups, which not only reduce the dimensions from 3D to quasi-2D but also improve their environmental stability. Quasi-2D perovskites have been actively explored to overcome the poor environmental stability of perovskite solar cells, owing to the hydrophobic nature of the large organic cations. Another important approach consisted of appropriately tuning the number of alkyl ammonium cations in the 3D perovskite precursor solution and providing mixed 2D/3D perovskites, which was also shown to be an effective method to produce stable and efficient perovskite solar cells by remarkably blocking the intrusion of moisture from the external atmosphere into the vulnerable 3D perovskite part. In this paper, we provide a brief review of recent advancements in two (quasi 2D) and mixed dimensional (2D/3D) Sn-based perovskite solar cells. Low dimensional (quasi-2D) and mixed dimensional (2D/3D) halide perovskites have emerged in the field of perovskite solar cells.