**4. Conclusions**

The high stability and relatively poor capability to convert light to electricity of low-dimensional perovskite films are the two aspects that need to be balanced. Based on the above analysis, we conclude that crystal growth direction and phase

distribution in the low-dimensional perovskite film determine the performance of the 2D PSCs. The crystal orientation in vertical direction and the proper phase distribution in favor of charge transfer are the targets for preparing high performance low-dimensional perovskite films. A few high-performance low-dimensional perovskite cells have emerged, showing high stability and efficiency comparable to 3D PSCs. Though the research on low-dimensional perovskite cells is far from enough and the crystal growth mechanism and carrier transport kinetics are still obscure, it is very promising to achieve efficient and stable photovoltaic devices using 2D perovskite materials as light absorbers.
