Spectroscopic Evidence of Localized Small Polarons in Low-Dimensional Ionic Liquid Lead-Free Hybrid Perovskites

Riki Subagyo, Pramitha Y.D. Maulida, Dominik Kowal, Sri Hartati, Rossyaila M. Muslimawati, Yulfi Zetra, Lina J. Diguna, Syafsir Akhlus, Muhammad H. Mahyuddin, Lei Zhang, Chi S. Tang, Caozheng Diao, Andrew T.S. Wee, Muhammad D. Birowosuto, A. Arramel*, Andrivo Rusydi*, Yuly Kusumawati*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Rational design is an important approach to consider in the development of low-dimensional hybrid organic−inorganic perovskites (HOIPs). In this study, 1-butyl-1-methyl pyrrolidinium (BMP), 1-(3-aminopropyl)imidazole (API), and 1-butyl-3-methyl imidazolium (BMI) serve as prototypical ionic liquid components in bismuth-based HOIPs. Element-sensitive X-ray absorption spectroscopy measurements of BMPBiBr4 and APIBiBr5 reveal distinct resonant excitation profiles across the N Kedges, where contrasting peak shifts are observed. These 1D-HOIPs exhibit a large Stokes shift due to the small polaron contribution, as probed by photoluminescence spectroscopy at room temperature. Interestingly, the incorporation of a small fraction of tin (Sn) into the APIBiBr5 (Sn/Bi mole ratio of 1:3) structure demonstrates a strong spectral weight transfer accompanied by a fast decay lifetime (2.6 ns). These phenomena are the direct result of Sn-substitution in APIBiBr5, decreasing the small polaron effect. By changing the active ionic liquid, the electronic interactions and optical responses can be moderately tuned by alteration of their intermolecular interaction between the semiconducting inorganic layers and organic moieties.

Original languageEnglish
Pages (from-to)54677-54691
Number of pages15
JournalACS applied materials & interfaces
Issue number47
Publication statusPublished - 2023


  • bismuth
  • halide perovskite
  • ionic liquids
  • small polaron
  • spectroscopy


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