Behavior of Methylammonium Dipoles in MAPbX(3) (X = Br and I)
- Author(s)
- Sharada Govinda, Bhushan P. Kore, Menno Bokdam, Pratibha Mahale, Abhinav Kumar, Somnath Pal, Biswajit Bhattacharyya, Jonathan Lahnsteiner, Georg Kresse, Cesare Franchini, Anshu Pandey, D. D. Sarma
- Abstract
Dielectric constants of MAPbX
3 (X = Br, I) in the 1 kHz-1 MHz range show strong temperature dependence near room temperature, in contrast to the nearly temperature-independent dielectric constant of CsPbBr
3. This strong temperature dependence for MAPbX
3 in the tetragonal phase is attributed to the MA
+ dipoles rotating freely within the probing time scale. This interpretation is supported by ab initio molecular dynamics simulations on MAPbI
3 that establish these dipoles as randomly oriented with a rotational relaxation time scale of ∼7 ps at 300 K. Further, we probe the intriguing possibility of transient polarization of these dipoles following a photoexcitation process with important consequences on the photovoltaic efficiency, using a photoexcitation pump and second harmonic generation efficiency as a probe with delay times spanning 100 fs-1.8 ns. The absence of a second harmonic signal at any delay time rules out the possibility of any transient ferroelectric state under photoexcitation.
- Organisation(s)
- Computational Materials Physics
- External organisation(s)
- Indian Institute of Science
- Journal
- The Journal of Physical Chemistry Letters
- Volume
- 8
- Pages
- 4113-4121
- No. of pages
- 9
- ISSN
- 1948-7185
- DOI
- https://doi.org/10.1021/acs.jpclett.7b01740
- Publication date
- 09-2017
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103025 Quantum mechanics, 103036 Theoretical physics, 103015 Condensed matter, 103009 Solid state physics
- Keywords
- ASJC Scopus subject areas
- Materials Science(all), Physical and Theoretical Chemistry
- Sustainable Development Goals
- SDG 7 - Affordable and Clean Energy
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/behavior-of-methylammonium-dipoles-in-mapbx3-x--br-and-i(0d633fe1-6825-474a-a82a-c9e479d194f0).html