Progress and perspective in Dion-Jacobson phase 2D layered perovskite optoelectronic applications

2D organic-inorganic halide perovskites have recently become the “next big thing” as promising candidates in optoelectronics. They possess higher moisture stability and lower ion migration compared to 3D perovskites due to the incorporation of bulky organic spacers. Compared to 2D Ruddlesden-Popper (RP) phase with two monoammoniums, 2D Dion-Jacobson (DJ) phase containing one diammonium has achieved a tighter connection between inorganic sheets due to formation of hydrogen bonds, resulting in higher crystal stability and more favorable charge transfer. RP phase solar cell has increased from 4.73% to 18.24% within six years, whereas DJ phase device shows a steep efficiency rise from 7.32% to 17.9% within only one year. Herein, this review provides in-depth understandings on optical property, orientation and charge transport, and energy band alignment of DJ phase perovskites, and raise perspectives that how they are affected by n value and diammoniums characteristics. The recent advances in solar cells, light-emitting diodes, and photodetectors have also been summarized. Finally, we discuss the remaining challenges of boosting device efficiency and try to answer the key scientific question that how to narrow phase distribution and engineer vertical orientation achieving the favorable energy alignment.