Journal
ADVANCED ENERGY MATERIALS
Volume 7, Issue 19, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.201700600
Keywords
hybrid materials; semiconductors; solar cells
Categories
Funding
- European Union via the Leitmarktwettbewerb NRW: Neue Werkstoffe [EFRE-0800120, NW-1-1-040h]
- BMBF project [03SF0517A]
- DFG Core Program Ferroic Cooling [Lu729/15]
Ask authors/readers for more resources
Due to the unprecedented rapid increase of their power conversion efficiency, hybrid organic-inorganic perovskites CH3NH3PbX3 (X = I, Br, Cl) can potentially revolutionize the world of solar cells. However, despite tremendous research activity, the origin of the exceptionally large diffusion length of their photogenerated charge carriers, that is, their low recombination rate, remains elusive. Using frequency and temperature-dependent dielectric measurements across the entire frequency spectrum, it is shown that the dielectric constant conserves very high values (>27) for frequencies below 1 THz in all three halides. This efficiently prevents photocarrier trapping and their recombination owing to the strong screening of charged entities. By combining ultrasonic and Raman spectroscopy with dielectric analysis, similarly large contributions to the dielectric constant are attributed to the dipolar disorder of the CH3NH3+ cations as well as lattice dynamics in the gigahertz range yielding dielectric constants of epsilon(stat) = 62 for the iodide, 58 for the bromide, and about 45 for the chloride below 1 GHz at room temperature. Disorder continuously reduces for decreasing temperature. Dipole dynamics prevail in the intermediate tetragonal phase. The low-temperature orthorhombic state is antipolar. No indications of ferroelectricity are found.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available