uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Nature of the excited state in lead iodide perovskite materials: Time-dependent charge density response and the role of the monovalent cation
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.ORCID iD: 0000-0001-6776-5460
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.ORCID iD: 0000-0003-2759-7356
2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 100, no 4, article id 045203Article in journal (Refereed) Published
Abstract [en]

Charge density response is responsible for the excited-state properties of lead iodide perovskites and is related to both the light absorption properties as well as subsequent electronic and lattice relaxation in the system, important for the working conditions of the material in solar cell applications. Here we investigate the nature of the excited state and its relation to pathways for electronic and lattice relaxations by performing time-dependent density-functional theory (TDDFT). Charge density response upon photoexcitation close to the band edge and deeper into the absorption spectra are investigated for three lead perovskite compounds with different A-site monovalent cations CsPbI3, CH2(NH2)(2)PbI3 (FAPbI(3)), and CH3NH3PbI3 (MAPbI(3)). The carrier cooling mechanism is analyzed and shows that the initial force acting on the nuclei follows the symmetry of the ground-state electronic structure upon photoexcitation with a force parallel to the polarization of the incoming light. This effect is investigated for the three different compounds and shows an initial force for induced ionic movement that depends on both the underlying symmetry of the inorganic lattice as well as on the type and orientation of the organic cation. The excess energy after thermalization under blue-light illumination is large enough for overcoming the activation energy for iodide migration and can thus trigger vacancy formation. Iodide vacancies are seen to be dipole-field compensated by the organic cation, with a shielding of the local field, and thus form an explanation for the defect tolerance found in these systems under photovoltaic operation. A partial charge transfer from the inorganic cage to the monovalent organic cation is predicted with TDDFT calculations for blue- and UV-light illumination with a population of antibinding orbitals in the N-H bond in both CH3NH3 (MA) and CH2(NH2)(2 )(FA), where the implication for this is discussed in terms of the intrinsic photo stability of organic cation containing lead perovskites. The results show the importance of a fundamental understanding of the excited-state properties of perovskite material to reveal the underlying mechanism for the defect tolerance and thus high photovoltaic performance when using organic dipolar cations as well as a rationale for using mixed halide perovskites to decrease the halide migration, effect of vacancy formation, and stability issues under blueand UV-light illumination.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC , 2019. Vol. 100, no 4, article id 045203
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-390785DOI: 10.1103/PhysRevB.100.045203ISI: 000475499700006OAI: oai:DiVA.org:uu-390785DiVA, id: diva2:1343267
Funder
Swedish Energy Agency, 43294-1Swedish National Infrastructure for Computing (SNIC), snic2018-3-228Swedish National Infrastructure for Computing (SNIC), snic20171-158Swedish National Infrastructure for Computing (SNIC), snic2018-3-352Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full text

Authority records BETA

Pazoki, MeysamEdvinsson, Tomas

Search in DiVA

By author/editor
Pazoki, MeysamEdvinsson, Tomas
By organisation
Solid State Physics
In the same journal
Physical Review B
Condensed Matter PhysicsPhysical Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 200 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf