From Cubic to Hexagonal: Electronic Trends across Metal Halide Perovskite Polytypes

Zhenzhu Li, Ji Sang Park, Alex M. Ganose, Aron Walsh

Research output: Contribution to journalArticlepeer-review

Abstract

Polytypes formed during the growth of metal halide perovskites can give rise to the formation of face-sharing sequences in corner-sharing octahedral networks. Here, the electronic influences of such structures, including the 6H and 12R phases, are found to be correlated with the fraction and stacking sequence of the face-sharing layers. The band gaps of polytypes feature a characteristic evolution from indirect to direct from pure hexagonal (2H) to cubic (3C) phases. Rather than arising from orbital mixing at the atomic level, a large band gap bowing of 1.96 eV in the CsPbI3 family was attributed to the long-range electronic interaction between octahedral building blocks. While retaining a high carrier velocity (∼2 × 105 m s-1), Fermi surface analysis further revealed a decrease of dimensionality from 3D to 2D in frequently observed polytypes, indicating a carrier blocking and anisotropic transport effect of hexagonal impurity phases, with consequences for their applications in solar cells and other optoelectronic devices.

Original languageEnglish
Pages (from-to)12695-12701
Number of pages7
JournalJournal of Physical Chemistry C
Volume127
Issue number26
DOIs
StatePublished - 6 Jul 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society

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