Pressure Engineering reveals the organic and inorganic interaction sites of hybrid perovskites

The Jilin University team reported a new strategy using pressure engineering to identify the interaction sites between the organic and inorganic forms of non-hydrogen bonded hybrid metal perovskites. This approach provides valuable guidance for designing materials with targeted optical properties and provides new insights into the photophysical mechanisms of hybrid perovskites.

“Previous studies have focused primarily on the effects of hydrogen bonding interactions of hybrid perovskites on the photophysical properties of materials,” said Guangzin Xiao, professor at the state’s leading laboratory of superhard materials at Jillin University. “The lack of exploration into the interaction mechanism of non-hydrogen-bonded hybrid perovskites is impeding the precise design of materials with target properties.”

As high-pressure engineering provides a powerful means to address discussions under environmental conditions, Xiao and his team sought to investigate specific sites of non-hydrogen-bonded hybrid perovskite (DBU) PBBR3 by invoking high pressures. Their work revealed that the spatial arrangement of the closest BR-N atomic pairs is a major factor in the organic and inorganic interaction.

This study was published in Journal Research.

In this study, the team synthesized Microd (DBU)PBBR3 using a high-temperature injection method, followed by a systematic investigation of high-pressure optical and structural properties. The researchers first found that material discharge showed reinforcement and blue shifts under pressure, with a calculated photoluminescent quantum yield of 86.6% under 5.0 GPA. Furthermore, photoluminescence lifetime measurements confirmed that non-radioactive recombination was suppressed under pressure.

The researchers also observed an unusually enhanced Raman mode in the pressure range where enhanced emissions occur. “This suggests a potential connection between the two phenomena,” Xiao said. They further analyzed the origin of Raman modes and identified them as corresponding to organic and inorganic interactions, possibly related to N-BR interactions.

It was the spatial arrangement of N and BR atoms, including distance and dihedral angle, that the team further analyzed structural evolution under pressure, conducted first-principles calculations, and identified the key factors affecting interaction strength. Isostructural phase transitions occurring at 5.5 GPA marked a turning point in evolutionary trends, Xiao said. The change in the primary compression direction initially increased the interaction strength of organic and inorganic, which decreased, and conformed to the evolution of optical properties.

“These findings fill the gap in the mechanisms of organic and inorganic interactions in non-hydrogen bonded hybrid halides and provide valuable guidelines for material design with target optical performance,” Xiao said.