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

Accepted version
Peer-reviewed

Type

Article

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Authors

Hutter, EM 
Gélvez-Rueda, MC 
Osherov, A 
Bulović, V 
Grozema, FC 

Abstract

Metal halide perovskites such as methylammonium lead iodide (CH3NH3PbI3) 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 CH3NH3PbI3 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.

Description

Keywords

51 Physical Sciences, 3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry, 7 Affordable and Clean Energy

Journal Title

Nature Materials

Conference Name

Journal ISSN

1476-4660
1476-4660

Volume Title

16

Publisher

Nature Publishing Group
Sponsorship
European Commission (622630)