Impact of microstructure on the electron-hole interaction in lead halide perovskites

Arman Mahboubi Soufiani, Zhuo Yang, Trevor Young, Atsuhiko Miyata, Alessandro Surrente, Alexander Pascoe, Krzysztof Galkowski, Mojtaba Abdi-Jalebi, Roberto Brenes, Joanna Urban, Nan Zhang, Vladimir Bulović, Oliver Portugall, Yi-Bing Cheng, Robin J. Nicholas, Anita Ho-Baillie, Martin A. Green, Paulina Plochocka, Samuel D. Stranks

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Despite the remarkable progress in the performance of devices based on the lead halide perovskite semiconductor family, there is still a lack of consensus on their fundamental photophysical properties. Here, using magneto-optical transmission spectroscopy we elucidate the impact of the microstructure on the Coulomb interaction between photo-created electron-hole pairs in methylammonium lead triiodide (MAPbI3) and the triple-cation lead mixed-halide composition, Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 (Cs: cesium, MA: methylammonium, FA: formamidinium) by investigating thin films with a wide range of grain sizes from tens of nanometers to microns. At low temperatures, in which thermal fluctuations of the interactions are frozen and the rotational disorder of the organic cation is negligible, the exciton binding energy and reduced effective mass of carriers remain effectively unchanged with grain size. We conclude that the microstructure plays a negligible role in the Coulomb interaction of the photo-created electron-hole pairs, in contrast to previous reports. This renewed understanding of the relationship between these fundamental electronic properties and the microstructure is critical for future fundamental studies and improving device design.

Original languageEnglish
Pages (from-to)1358-1366
Number of pages9
JournalEnergy & Environmental Science
Issue number6
Publication statusPublished - 1 Jun 2017

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