Research ArticleMOLECULAR ELECTRONICS

Ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity

See allHide authors and affiliations

Science Advances  29 Sep 2017:
Vol. 3, no. 9, e1701017
DOI: 10.1126/sciadv.1701017
  • Fig. 1 A cartoon of the devices studied and the chemical structure of the investigated oFESC compounds and their supramolecular organization.

    Semiconducting cores are shown in blue, and dipolar side groups are shown in red. (I) Structures of PBI-oVDF and Pc-oVDF. (II) Structure of SubPc-amide. For details of the synthesis and characterization, see the Supplementary Materials.

  • Fig. 2 Simultaneous switching of polarization and conductivity in SubPc-amide.

    Ferroelectric polarization (A) and current (B) versus applied bias for a Au/SubPc-amide/Au diode. Polarization and current are separate measurements on the same device. Thin dotted lines indicate the coercive voltage; red dashed lines are fits to a sum of ohmic (Eq. 1) and SCLC (Eq. 2) contributions, showing that conductivity is bulk-limited. Arrows indicate loop sense. Device film thickness L = 1 μm, T = 130° to 135°C.

  • Fig. 3 Simultaneous switching of polarization and conductivity in PBI-oVDF and Pc-oVDF.

    Ferroelectric polarization (A and C) and current (B and D) versus bias for oFESC diodes based on PBI-oVDF (A and B) and Pc-oVDF (C and D). Polarization and current are separate measurements on the same device. Black and gray lines indicate different measurements; red dashed lines are fits consisting of ohmic (Eq. 1) and SCLC (Eq. 2) contributions. Arrows indicate loop sense. (A and B) L = 0.8 μm, T = 55° to 60°C. (C and D) L = 1 μm, T = 40° to 45°C. For jV curves on linear scale, see fig. S15.

  • Fig. 4 Conductivity and polarization decay at the same rate.

    Retention of polarization (A) and current (B) in PBI-oVDF and Pc-oVDF oFESC diodes. Retention is measured by poling the diode and reading out the remaining polarization and the on-current after a waiting time t. During the waiting time, the device is grounded. Polarization and current measurements were taken successively on the same devices. Y axes are normalized to the values at t = 0 s; joff is the current in the fully depolarized state. Other parameters are shown in Fig. 3.

  • Fig. 5 Two-site model for bulk conductivity modulation based on Marcus hopping.

    (A) Electrostatic potentials of a single molecule (dark and light blue lines) and their sum (red line) of the stack of molecules shown in the lower half. The asymmetry of this potential energy landscape leads to a nonequivalence of hopping with the polarization P directed along (B) and against (D) the field F. Symmetric Marcus potentials are plotted as dashed curves in (B) and (D). The difference in energy barrier ΔE between the two polarization states causes a difference in conductivity at finite field. The resulting on/off ratio at a field of 100 V/μm is given in (C) as a function of reorganization energy λ and site energy difference ΔE0.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/9/e1701017/DC1

    section S1. Synthesis and material characterization

    section S2. Device alignment and characterization

    section S3. Detailed analysis of jV curves

    section S4. jV curves on linear scale

    section S5. Details of the two-site model

    scheme S1. Synthetic method for the preparation of PBI-oVDF and Pc-oVDF.

    scheme S2. Synthetic method for the preparation of SubPc-amide.

    fig. S1. Structure of PBI-oVDF.

    fig. S2. Characterization of PBI-oVDF.

    fig. S3. Structure of Pc-oVDF.

    fig. S4. Characterization of Pc-oVDF.

    fig. S5. Structure of SubPc-amide.

    fig. S6. NMR spectra of SubPc-amide.

    fig. S7. Mass spectroscopy of SubPc-amide.

    fig. S8. POM on SubPc.

    fig. S9. Principle of the DWM.

    fig. S10. Typical charging curves obtained by the DWM.

    fig. S11. Analysis of a Pc-oVDF oFESC diode after incomplete field annealing.

    fig. S12. Detailed analysis of current-voltage characteristics of oFESC diodes.

    fig. S13. Hysteresis loop and current-voltage characteristics of PVDF-TrFE.

    fig. S14. Same data as in Fig. 2B, plotted on linear scale.

    fig. S15. Same data as in Fig. 3 (B and D), plotted on linear scale.

    fig. S16. The potential landscape for hopping in the two-site model.

    fig. S17. Geometry of the SubPc-amide molecule.

    fig. S18. Experimental and simulated on/off ratio as a function of applied field.

    table S1. Model parameters.

    References (3441)

  • Supplementary Materials

    This PDF file includes:

    • section S1. Synthesis and material characterization
    • section S2. Device alignment and characterization
    • section S3. Detailed analysis of jV curves
    • section S4. jV curves on linear scale
    • section S5. Details of the two-site model
    • scheme S1. Synthetic method for the preparation of PBI-oVDF and Pc-oVDF.
    • scheme S2. Synthetic method for the preparation of SubPc-amide.
    • fig. S1. Structure of PBI-oVDF.
    • fig. S2. Characterization of PBI-oVDF.
    • fig. S3. Structure of Pc-oVDF.
    • fig. S4. Characterization of Pc-oVDF.
    • fig. S5. Structure of SubPc-amide.
    • fig. S6. NMR spectra of SubPc-amide.
    • fig. S7. Mass spectroscopy of SubPc-amide.
    • fig. S8. POM on SubPc.
    • fig. S9. Principle of the DWM.
    • fig. S10. Typical charging curves obtained by the DWM.
    • fig. S11. Analysis of a Pc-oVDF oFESC diode after incomplete field annealing.
    • fig. S12. Detailed analysis of current-voltage characteristics of oFESC diodes.
    • fig. S13. Hysteresis loop and current-voltage characteristics of PVDF-TrFE.
    • fig. S14. Same data as in Fig. 2B, plotted on linear scale.
    • fig. S15. Same data as in Fig. 3 (B and D), plotted on linear scale.
    • fig. S16. The potential landscape for hopping in the two-site model.
    • fig. S17. Geometry of the SubPc-amide molecule.
    • fig. S18. Experimental and simulated on/off ratio as a function of applied field.
    • table S1. Model parameters.
    • References (34–41)

    Download PDF

    Files in this Data Supplement:

Navigate This Article