Double Charged Surface Layers in Lead Halide Perovskite Crystals

Smritakshi P. Sarmah, Victor M. Burlakov, Emre Yengel, Murali Banavoth, Erkki Alarousu, Ahmed M. El-Zohry, Chen Yang, Mohd Sharizal Alias, Ayan A. Zhumekenov, Makhsud I. Saidaminov, Nam Chul Cho, Nimer Wehbe, Somak Mitra, Idris A. Ajia, Sukumar Dey, Ahmed Mansour, Maged Abdelsamie, Aram Amassian, Iman S. Roqan, Boon S. OoiAlain Goriely, Osman Bakr, Omar F. Mohammed

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.
Original languageEnglish (US)
Pages (from-to)2021-2027
Number of pages7
JournalNano Letters
Volume17
Issue number3
DOIs
StatePublished - Feb 7 2017

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