Ion migration is associated with hysteresis observed in halide perovskite-based solar cells and light-emitting diodes, however, it is crucial for their effective performance in memory devices. In the halide perovskites field, a direct link between the average/local structure and the preferred ion migration hopping pathway has yet to be established. Herein, we utilize the solvent acidolysis crystallization technique to grow various halide-deficient methylammonium copper halide crystals where perovskite-type layers are found. Through synchrotron X-ray powder diffraction (XRPD) and pair distribution function (PDF) analyses, we identify the halogen vacancy site in the copper halide octahedra, the octahedra tilting, and the thermal vibrations of the atoms around their average positions. We correlate the variations in these parameters to the hysteresis observed in the current-voltage curves and subsequently to the ON/OFF ratios of proof-of-concept memory devices fabricated using inert Pt electrodes. Furthermore, our best ON/OFF ratio of ∼10 from our Pb-free devices compares well to the results obtained from two-dimensional Pb-based devices utilizing inert electrodes.

Impact of local structure on halogen ion migration in layered methylammonium copper halide memory devices

Aniruddha Ray;Davide Spirito;Federico Locardi;Liberato Manna;
2020-01-01

Abstract

Ion migration is associated with hysteresis observed in halide perovskite-based solar cells and light-emitting diodes, however, it is crucial for their effective performance in memory devices. In the halide perovskites field, a direct link between the average/local structure and the preferred ion migration hopping pathway has yet to be established. Herein, we utilize the solvent acidolysis crystallization technique to grow various halide-deficient methylammonium copper halide crystals where perovskite-type layers are found. Through synchrotron X-ray powder diffraction (XRPD) and pair distribution function (PDF) analyses, we identify the halogen vacancy site in the copper halide octahedra, the octahedra tilting, and the thermal vibrations of the atoms around their average positions. We correlate the variations in these parameters to the hysteresis observed in the current-voltage curves and subsequently to the ON/OFF ratios of proof-of-concept memory devices fabricated using inert Pt electrodes. Furthermore, our best ON/OFF ratio of ∼10 from our Pb-free devices compares well to the results obtained from two-dimensional Pb-based devices utilizing inert electrodes.
File in questo prodotto:
File Dimensione Formato  
Just accepted.pdf

accesso aperto

Tipologia: Documento in Post-print
Dimensione 2.25 MB
Formato Adobe PDF
2.25 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/1020656
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 13
  • ???jsp.display-item.citation.isi??? 13
social impact