Direct-indirect character of the bandgap in methylammonium lead iodide perovskite

Eline M. Hutter, María C. Gélvez-Rueda, Anna Osherov, Vladimir Bulović, Ferdinand C. Grozema, Samuel D. Stranks, Tom J. Savenije*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

294 Citations (Scopus)
6 Downloads (Pure)

Abstract

Metal halide perovskites such as methylammonium lead iodide (CH3 NH3 PbI3) are generating great excitement due to their outstanding optoelectronic properties, which lend them to application in high-efficiency solar cells and light-emission devices. However, there is currently debate over what drives the second-order electron-hole recombination in these materials. Here, we propose that the bandgap in CH3 NH3 PbI3 has a direct-indirect character. Time-resolved photo-conductance measurements show that generation of free mobile charges is maximized for excitation energies just above the indirect bandgap. Furthermore, we find that second-order electron-hole recombination of photo-excited charges is retarded at lower temperature. These observations are consistent with a slow phonon-assisted recombination pathway via the indirect bandgap. Interestingly, in the low-temperature orthorhombic phase, fast quenching of mobile charges occurs independent of the temperature and photon excitation energy. Our work provides a new framework to understand the optoelectronic properties of metal halide perovskites and analyse spectroscopic data.

Original languageEnglish
Pages (from-to)115-120
Number of pages6
JournalNature Materials
Volume16
Issue number1
DOIs
Publication statusPublished - 2017

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