Exciton Self-Trapping for White Emission in 100-Oriented Two-Dimensional Perovskites via Halogen Substitution

Ying Han, Jun Yin, Guangyue Cao, Zixi Yin, Yiwei Dong, Runan Chen, Yu Zhang, Nengxu Li, Shengye Jin, Omar F. Mohammed, Bin-Bin Cui, Qi Chen

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Low-dimensional organic-inorganic hybrid lead halides have opened up a new frontier in single-component phosphors for white emission, which stems from self-trapped excitons (STEs), where STE states are dependent on lattice deformation, involving interactions between an inorganic skeleton and organic cations to consequently affect electron-phonon coupling. Herein, to decouple the crystal structure dominator on emission mechanisms, we employ the protonated benzimidazole as organic cations to synthesize two 100-oriented two-dimensional (2D) perovskites with Br- or Cl- as halogen anions, separately. Interestingly, even with a similar single layered crystal structure that is almost distortion-free in an inorganic octahedral framework, the two as-synthesized perovskites show distinct emission mechanisms. The underlying halogen regulatory mechanism is unveiled. In addition to changing the lattice deformation energy and self-trapping energy of STEs, the halogen substitution results in a 10-fold enhancement in electron-phonon coupling that affects STE dynamics. Therefore, this suggests a general design principle to tailor electron-phonon coupling in low-dimensional perovskites for broadband white emission.
Original languageEnglish (US)
Pages (from-to)453-460
Number of pages8
JournalACS Energy Letters
DOIs
StatePublished - Dec 28 2021

Bibliographical note

KAUST Repository Item: Exported on 2022-01-25
Acknowledgements: This work was supported by funding from the National Natural Science Foundation (22075022 and 21703008). We also thank the “Cultivate Creative Talents Project” of Beijing Institute of Technology (BIT) for financial support. The research reported in this publication was also supported by the King Abdullah University of Science and Technology (KAUST).

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