Dimensionality regulation in tin halide perovskite solar cells: Toward high performance and stability

Abstract

Tin halide perovskites (THPs) have received extensive attention due to their low toxicity and excellent optoelectronic properties, and are considered to be the most promising alternatives to develop efficient lead-free perovskite solar cells. However, due to the unique and inherent characteristics of Sn2+ being easily oxidized to Sn4+ and fast crystallization, tin perovskite solar cells (TPSCs) show relatively poor performance and stability, compared to the lead counterparts. Recently, the introduction of bulky organic spacers into three-dimensional (3D) THPs for dimensional regulation can not only prevent the intrusion of water and oxygen, but also inhibit the self-doping effect and ion migration. In this review, we will detail how dimensional regulation enables TPSCs with high performance and superior stability. First, we summarize the intrinsic properties of THPs and analyze the root causes of their poor performance and instability. Next, we discuss the specific structure and types of the dimensional regulation strategy. Then, the mechanism of dimensional regulation is discussed in detail, mainly from inhibiting the Sn2+ oxidation, optimizing crystallization, passivating defects, and improving energy level alignment. Finally, future challenges and prospects for dimensional regulation are elaborated to help researchers develop more efficient and stable TPSCs.