Tuning Napththalenediimide Cations for Incorporation intoRuddlesden-Popper-Type Hybrid Perovskites

Layered hybrid organic-inorganic perovskite (LHOIP) materialsconstructed with low-band-gap chromophore-based organic spacer cations are anemerging class of materials that promise unique tunability of their optoelectronicproperties. However, the large size of such chromophore-based spacer cationschallenges their incorporation into a layered perovskite structure and requires furtherinsight into the layered perovskite phase formation mechanism. Herein, we report thepreparation and incorporation of asymmetric naphthalenediimide (NDI) spacerchromophore cations with different amine-bearing alkyl linker chains into thinfilmsof LHOIPs. Usingin situUV-vis spectroscopic kinetic studies of the quantum wellformation, we show that shorter linker chain lengths require higher annealingtemperatures to form the LHOIP structure. Avrami analysis of the layered perovskiteformation shows a larger Avrami coefficient (n= 3.64) for short linker chain-bearing cations compared to that for longer alkyl chain-bearing cations (n= 2.43), suggesting an evolution from three-dimensional to quasi-two-dimensional crystal growth with increasinglinker chain length. Additionally, transient absorption spectroscopy and broad-bandfluorescent upconversion spectroscopy indicatefast photoinduced charge transfer from the inorganic layer to the electron-accepting NDI-spacer cation.

Automated summary

This study reports the preparation and incorporation of asymmetric naphthalenediimide (NDI) spacer chromophore cations with different amine-bearing alkyl linker chains into thin films of layered hybrid organic-inorganic perovskite (LHOIP) materials. In situ UV-vis spectroscopic kinetic studies reveal that shorter linker chain lengths require higher annealing temperatures to form the LHOIP structure. Avrami analysis of the layered perovskite formation demonstrates an evolution from three-dimensional to quasi-two-dimensional crystal growth with increasing linker chain length.