Extremely slow photoconductivity response of CH3NH 3PbI3 perovskites suggesting structural changes under working conditions

Ronen Gottesman, Eynav Haltzi, Laxman Gouda, Shay Tirosh, Yaniv Bouhadana, Arie Zaban*, Edoardo Mosconi, Filippo De Angelis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

304 Scopus citations

Abstract

Photoconductivity measurements of CH3NH3PbI 3 deposited between two dielectric-protected Au electrodes show extremely slow response. The CH3NH3PbI3, bridging a gap of ∼2000 nm, was subjected to a DC bias and cycles of 5 min illumination and varying dark duration. The approach to steady -state photocurrent lasted tens of seconds with a strong dependence on the dark duration preceding the illumination. On the basis of DFT calculations, we propose that under light + bias the methylammonium ions are freed to rotate and align along the electric field, thus modifying the structure of the inorganic scaffold. While ions alignment is expected to be fast, the adjustment of the inorganic scaffold seems to last seconds as reflected in the extremely slow photoconductivity response. We propose that under working conditions a modified, photostable, perovskite structure is formed, depending on the bias and illumination parameters. Our findings seem to clarify the origin of the well-known hysteresis in perovskite solar cells.

Original languageAmerican English
Pages (from-to)2662-2669
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume5
Issue number15
DOIs
StatePublished - 7 Aug 2014
Externally publishedYes

Keywords

  • dipole alignment
  • light harvesting material
  • photoconductivity
  • solar cells

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