Researchers reveal the origin of the stable Dion-Jacobson 2D perovskites

Yin-Yang theory is an ancient Chinese philosophy in which the Yin-Yang forces are interdependent and work in opposition to each other to create balance.

Recently, inspired by this ancient theory, a research team led by Professor Guo Shen and Professor Li Kan of the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) revealed the origin of stable Dione-Jacobson (DJ) two-dimensional (2D) perovskite materials. ).

Their findings have been published in Joule.

DJ 2D perovskites, a class of organic and inorganic hybrid perovskite materials, have been widely used in many optoelectronic applications.

Compared with traditional 3D perovskites with intrinsically low stability, 2D perovskites including Ruddlesden-Popper (RP) phase and DJ phase are more attractive due to their enhanced stability, especially DJ 2D perovskites based on organic diammonium cations and inorganic lead iodide octahedral, which Containing higher structural stability than those of RP.

However, some DJ 2D perovskites are not as robust and even degrade more easily than their 2D RP counterparts, which has led to controversy about their stability. These contradictory research results prompted the scientists to elucidate the stabilization mechanism of DJ 2D perovskites with different diammonium cations.

In this study, the researchers show that the stability of DJ 2D perovskites was determined by the hardness of organic diammonium cations, which can induce co-adaptation of organic and inorganic components to stabilize the 2D structure. Specifically, the intermediate cation stiffness allowed the organic diammonium and the inorganic octahedral to organize their geometries in mutual adaptation in order to reach a steady state.

This mechanism may provide guidance for researchers who wish to consciously manipulate the stability of DJ 2D perovskites by adjusting the cation stiffness.

“Similar to the two extremes in Yin-Yang theory, the organic cations and the inorganic octahedral in DJ 2D perovskites are interconnected with alternating hydrogen bonds and when both parts can adjust their geometries to adapt to each other, strong connections are desirable,” said the professor. . power. “In this way, organic cations with moderate hardness will play a crucial role in the interfacial coordination process because they have a certain degree of freedom in regulating the geometry and the inorganic moiety can change its composition as well.”