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Understanding Method-Dependent Differences in Urbach Energies in Halide Perovskites

Title data

Witt, Christina ; Schötz, Konstantin ; Köhler, Anna ; Panzer, Fabian:
Understanding Method-Dependent Differences in Urbach Energies in Halide Perovskites.
In: The Journal of Physical Chemistry. (8 April 2024) .
ISSN 1932-7447
DOI: https://doi.org/10.1021/acs.jpcc.3c07293

Official URL: Volltext

Abstract in another language

The Urbach energy as a measure of energetic disorder is an important characteristic of semiconductors to evaluate their optoelectronic functionality. However, discrepancies occur in Urbach energy values EU determined via different measurement and analysis methods, whose origin of a profound understanding is still missing. To reliably analyze the origin of such discrepancies, we recorded quasi-simultaneously temperature-dependent absorption and photoluminescence (PL) spectra of halide perovskite (MAPbI3) thin-film and single-crystal samples. Performing profound Urbach analyses in an extended energy range down to 0.2 eV below the bandgap, we find energy-range-dependent exaggeration effects on Urbach energy values to be only present in the near bandgap region (∼0.02 eV below the bandgap), where non-Urbach absorption states start to contribute. Besides that, generally lower EU values and a lower temperature-dependence of EU are obtained from PL than from absorption, which originates from the sensitivity of PL for sites with lower energetic disorder and/or higher phonon energies in the excited-state geometry. Thus, our work is sensitized to proper interpretation and comparison of EU values and contributes to developing a more fundamental understanding of semiconductor materials.The Urbach energy as a measure of energetic disorder is an important characteristic of semiconductors to evaluate their optoelectronic functionality. However, discrepancies occur in Urbach energy values EU determined via different measurement and analysis methods, whose origin of a profound understanding is still missing. To reliably analyze the origin of such discrepancies, we recorded quasi-simultaneously temperature-dependent absorption and photoluminescence (PL) spectra of halide perovskite (MAPbI3) thin-film and single-crystal samples. Performing profound Urbach analyses in an extended energy range down to 0.2 eV below the bandgap, we find energy-range-dependent exaggeration effects on Urbach energy values to be only present in the near bandgap region (∼0.02 eV below the bandgap), where non-Urbach absorption states start to contribute. Besides that, generally lower EU values and a lower temperature-dependence of EU are obtained from PL than from absorption, which originates from the sensitivity of PL for sites with lower energetic disorder and/or higher phonon energies in the excited-state geometry. Thus, our work is sensitized to proper interpretation and comparison of EU values and contributes to developing a more fundamental understanding of semiconductor materials.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics II - Optoelectronics of Soft Matter > Chair Experimental Physics II - Optoelectronics of Soft Matter - Univ.-Prof. Dr. Anna Köhler
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 11 Apr 2024 07:19
Last Modified: 11 Apr 2024 07:19
URI: https://eref.uni-bayreuth.de/id/eprint/89292