Limitations and solutions for achieving high-performance perovskite tandem photovoltaics

The large light absorption coefficient, long carrier diffusion length, and high defect tolerance enable organic-inorganic lead halide perovskites for excellent photovoltaic performance. The highest certified power conversion efficiency of single-junction perovskite solar cells (PSCs) has reported 25.5%. Besides, the bandgap of perovskites can be tuned by engineering their composition. These merits have made perovskites promising candidates for tandem photovoltaics, which can cross over the Shockley-Queisser limit of single-junction PSCs with economic costs. However, there are yet some hurdles in the wide-bandgap and narrow-bandgap subcells as well as interconnected layers (ICLs), which limit the commercial applications of perovskite tandem solar cells (PTSCs). In this review, we summarize the major scientific and technical limitations of PTSCs. We firstly demonstrate the configurations and working principles of PTSCs. Then, the developments of front subcells and rear subcells are discussed. Their main drawbacks, implemented technologies, and underlying mechanisms are analyzed in detail. Subsequently, the progress of ICLs which are responsible for guaranteeing continuous current in 2 T PTSCs are discussed. In addition, the stability of PTSCs is also summarized. The purpose of this review is to map and thrive the future development of PTSCs.