Role of Polar Phonons in the Photo Excited State of Metal Halide Perovskites

Autor(en)

Menno Bokdam, Tobias Sander, Alessandro Stroppa, Silvia Picozzi, D. D. Sarma, Cesare Franchini, Georg Kresse

Abstrakt

The development of high efficiency perovskite solar cells has sparked a multitude of measurements on the optical properties of these materials. For the most studied methylammonium(MA)PbI 3 perovskite, a large range (6-55 meV) of exciton binding energies has been reported by various experiments. The existence of excitons at room temperature is unclear. For the MAPbX 3 perovskites we report on relativistic Bethe-Salpeter Equation calculations (GW-BSE). This method is capable to directly calculate excitonic properties from first-principles. At low temperatures it predicts exciton binding energies in agreement with the reported â € large' values. For MAPbI 3, phonon modes present in this frequency range have a negligible contribution to the ionic screening. By calculating the polarization in time from finite temperature molecular dynamics, we show that at room temperature this does not change. We therefore exclude ionic screening as an explanation for the experimentally observed reduction of the exciton binding energy at room temperature and argue in favor of the formation of polarons.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Consiglio Nazionale delle Ricerche, Indian Institute of Science

Journal

Scientific Reports

Band

6

Anzahl der Seiten

8

ISSN

2045-2322

DOI

https://doi.org/10.1038/srep28618

Publikationsdatum

06-2016

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/26d02102-6218-4e77-b34b-4ab5015d7824