Highly efficient and stable tandem solar cells based on halide perovskites (Conference Presentation)

The tandem configuration consisting of two or more solar cells is practically the only approach to overcome the Shockley-Queisser limit, as evidenced by the III-V multijunction solar cells. From theoretical calculation, it has been found that the combination of a top cell with a large bandgap energy (e.g. 1.5~1.7 eV) and a bottom cell with a low bandgap energy (e.g. 1.0~1.1 eV) can lead to a conversion efficiency higher than 30%. Given that the bandgap energy of most commercial single junction solar cells is around 1.1 eV, the perovskite solar cells with a bandgap energy around 1.6 eV must be a very promising candidate for the top cell of tandem solar cells. In this presentation, I will discuss the essential requirements for preparing highly performing perovskite top cells of perovskite-based tandem solar cells. Firstly, the strategies for improving the performance of the p-i-n type planar perovskite solar cell, mostly focusing on the interfacial charge transfer, will be introduced. After a series of interfacial engineering procedures to the charge extraction layers, a conversion efficiency as high as 19% could be achieved. Secondly, strategies for fabricating transparent perovskite solar cells with a TCO top electrode layer will be discussed. Finally, some of the recent results on the highly efficient (> 23%) tandem solar cells incorporating the transparent perovskite top cell will be introduced.